Digital video signal record and playback device and method for recording and playing back the same

ABSTRACT

A digital video signal record and playback device for recording on a recording medium a digital video signal coded by using a motion compensation prediction and an orthogonal transform and playing back data from the recording medium. In a data arrangement of a digital video signal, an I picture which can be independently represented in a picture is divided into n areas in the vertical direction, and the data is arranged from the front of one GOP in the unit of area by giving a priority to an area located at the center of the screen. A playback picture is outputted by playing back the I picture read from the recording medium in the unit of area unit. In the case where the whole I picture area cannot be read within a definite time, the area which cannot be read are interpolated by the use of the data of the preceding screen.

BACKGROUND OF INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a digital video signal recordand playback device for recording and playing back a digital videosignal, and more particularly to a digital video signal record andplayback device for recording and playing back on a medium such as anoptical disc or the like a digital video signal coded on the basis of amotion compensation prediction and an orthogonal conversion.

[0003] 2. Description of Related Art

[0004]FIG. 1 is a block circuit diagram of a conventional optical discrecord and playback device shown in the Japanese Patent ApplicationLaid-Open No. HEI 4-114369 (1992). Referring to FIG. 1, referencenumeral 201 denotes an A/D converter for converting a video signal, anaudio signal or the like into digital information. Reference numeral 202denotes a data compressing circuit, 203 a frame sector convertingcircuit for converting compressed data into sector data which is equalto integer times of a frame cycle, 204 an error correction coder foradding the error correction signal to sector data, 205 a modulator formodulating interference between codes in a recording medium into apredetermined modulation code to reduce the interference, 206 a laserdriving circuit for modulating laser light in accordance with amodulation code, and 207 a laser output switch. Further, referencenumeral 208 denotes an optical head for emitting laser light, 209 anactuator for tracking a light beam emitted from the optical head 208,210 a traverse motor for sending the optical head 208, 211 a disc motorfor rotating an optical disc 212, 219 a motor driving circuit, 220 afirst control circuit and 221 a second control circuit. Further,reference numeral 213 denotes a playback amplifier for amplifying aplayback signal from the optical head 208. Reference numeral 214 denotesa demodulator for obtaining data from a recorded modulation signal, 215an error correction decoder, 216 a frame sector inverse convertingcircuit, 217 a data extending circuit for extending the compressed data,218 a D/A converter for converting extended data into, for example, ananalog video signal and an audio signal.

[0005]FIG. 2 is a block circuit diagram showing an inside structure ofthe data compressing circuit 202 in FIG. 1. In FIG. 2, a digital videosignal inputted from the A/D converter 201 is inputted into a memorycircuit 301. A video signal 321 outputted from the memory circuit 301 isgiven to a first input of a subtracter 302 and a second input of amotion compensation predicting circuit 310. An output of the subtracter302 is inputted to a quantizer 304 via a DCT (discrete cosine transform)circuit 303. An output of the quantizer 304 is given to an input of atransmission buffer 306 via a variable-length encoder 305. An output ofthe transmission buffer 306 is outputted to the frame sector convertingcircuit 203. In the meantime, an output of the quantizer 304 is inputtedto the inverse DCT circuit 308 via an inverse quantizer 307. An outputof the inverse DCT circuit 308 is given to a first input of an adder309. An output 322 of the adder 309 is given to a first input of amotion compensation predicting circuit 310. An output 323 of the motioncompensation predicting circuit 310 is given to a second input of theadder 309 and a second input of the subtracter 302.

[0006]FIG. 3 is a block circuit diagram showing an inside structure ofthe motion compensation predicting circuit 310 in FIG. 2. In FIG. 3, theoutput 322 of the adder 309 is given to an input terminal 401 a whilethe output 321 of the memory circuit 301 is given to an input terminal401 b. The signal 322 inputted from the input terminal 401 a is inputtedto a frame memory 404 a or a frame memory 404 b via a switch 403. Areference picture outputted from the frame memory 404 a is given to afirst input of a motion vector detecting circuit 405 a. The video signal321 inputted from the input terminal 401 b is inputted to a second inputof the motion vector detecting circuit 405 a. An output of the motionvector detecting circuit 405 a is inputted to a prediction mode selector406. In the meantime, the reference picture outputted from the framememory 404 b is given to a first input of a motion vector detectingcircuit 405 b. The video signal 321 inputted from the input terminal 401b is given to a second input of the motion vector detecting circuit 405b. The output of the motion vector detecting circuit 405 b is given tothe second input of the prediction mode selector 406. The video signal321 inputted from the input terminal 401 b is given to a third input ofthe prediction mode selector 406. A zero signal is given to a secondinput of a switcher 407. A second output of the prediction mode selector406 is given to a third input of the switcher 407. The output 323 of theswitcher 407 is outputted from a output terminal 402.

[0007]FIG. 4 is a block circuit diagram showing an inside structure ofthe data extending circuit 217 in FIG. 1. In FIG. 4, the video signalinputted from the frame sector inverse converting circuit 216 isinputted to a reception buffer 501. An output from the reception buffer501 is inputted to a variable-length decoder 502, and the outputtherefrom is inversely quantized at an inverse quantizer 503. Then, theoutput is subjected to an inverse discrete cosine transform at aninverse DCT circuit 504. The output is given to a first input of anadder 506. In the meantime, the output of the reception buffer 501 isgiven to a prediction data decoding circuit 505 while an output of theprediction data decoding circuit 505 is given to a second output of theadder 506. The output of the adder 506 is outputted to the D/A converter218 via a memory circuit 507.

[0008] Next, an operation of the device will be explained. As one highefficiency coding mode in the case of coding a video signal, there is ancoding algorithm by means of a MPEG (Moving Picture Expert Group) mode.This is a hybrid coding mode which combines an inter-frame predictioncoding using a motion compensation prediction and an intra-frameconversion coding. This conventional example uses a data compressingcircuit 202 having a structure shown in FIG. 2 and adopts theaforementioned MPEG mode.

[0009]FIG. 5 shows a simplified data arrangement structure (layerstructure) of MPEG mode. In FIG. 5, reference numeral 621 denotes asequence layer comprising a group of pictures (hereinafter referred toas “GOP”) comprising a plurality of frame data items, 622 a GOP layercomprising several pictures (screens), 623 a slice which divides onescreen into several blocks, 624 a slice layer which has severalmacroblocks, 625 a macroblock layer, 626 a block layer which consists of8 pixels×8 pixels.

[0010] This macroblock layer 625 is a block which consists of a leastunit of 8 pixels×8 pixels, for example, in the MPEG mode. This block isa unit for performing DCT. At this time, a total of 6 blocks, includingadjacent four Y signal blocks, one Cb block which corresponds to the Ysignal blocks in position, and one Cr block are referred to asmacroblocks. A plurality of these macroblocks constitute a slice. Inaddition, the macroblocks constitute a minimum unit of a motioncompensation prediction, and a motion vector for the motion compensationprediction is formed in macroblock units.

[0011] Subsequently, a process for the inter-frame prediction codingwill be explained. FIG. 6 shows an outline of the inter-frame predictioncoding. Pictures are divided into three types, namely an intra-framecoded picture (hereinafter referred to as an I picture), a one directionprediction coded picture (hereinafter referred to as a P picture), and aboth direction prediction coded picture (hereinafter referred to as a Bpicture).

[0012] For example, in the case where one picture out of N pictures isset to I picture, one picture out of M pictures is set to P picture or Ipicture, (N×n+M)th picture constitutes an I picture, (N×n+M×m)th picture(m≠1) constitutes a P picture, pictures from (N×n+M×m+1)th picture to(N×n+M×m+M−1)th picture constitute B pictures, where n and m areintegers and 1≦m≦N/M. At this time, pictures from (N×n+1)th picture to(N×n+N)th picture are referred to as a GOP (group of pictures) insummary.

[0013]FIG. 6 shows a case in which symbols N and M are defined as N=15and M=3. in FIG. 6, the I picture is not subjected to the inter-frameprediction but only to the intra-frame conversion coding. The P pictureis subjected to a prediction from the I picture immediately before the Ppicture or from the P picture. For example, the 6th picture in FIG. 6 isa P picture. The 6th picture is subjected to the prediction from the 3rdI picture. Further, the 9th P picture in FIG. 6 is subjected to theprediction from the 6th P picture. The B picture is subjected to theprediction from I picture or the P picture immediately before and afterthe B picture. For example, in FIG. 6, the 4th and 5th B pictures issubjected to the prediction both from the 3rd I picture and the 6th Ppicture. Consequently, the 4th and 5th pictures is subjected to codingafter coding of the 6th picture.

[0014] Then, an operation of a data compressing circuit 202 will beexplained in accordance with FIG. 2. The memory circuit 301 outputs thedigital video picture signals which are inputted after rearranging thesignals in the coding order. In other words, as described above, forexample, the first B picture is coded after the 3rd I picture in FIG. 6.Consequently, the order of pictures are rearranged. FIG. 7 shows anoperation of this rearrangement. An picture sequence inputted as shownin FIG. 7A is outputted in the order shown in FIG. 7B.

[0015] Further, the video signal 321 outputted from the memory circuit301 is subjected to DCT in the direction of space axis after adifference between pictures from the prediction picture 323 outputtedfrom the motion compensation predicting circuit 310 at the subtracter302 to reduce the redundancy in the direction of the time axis. Theconverted coefficient is quantized and variable-length coded followed bybeing outputted via the transmission buffer 306. In the meantime, thequantized conversion coefficient is inversely quantized and is subjectedto an inverse DCT. After that, the coefficient is added to theprediction picture 323 at the adder 309 and a decoded picture 322 isobtained. The decoded picture 322 is inputted to the motion compensationpredicting circuit 310 for the subsequent coding of pictures.

[0016] Subsequently, an operation of the motion compensation predictingcircuit 310 will be explained in accordance with FIG. 3. The motioncompensation predicting circuit 310 uses two reference pictures whichare stored in the frame memory 404 a and the frame memory 404 b toperform a motion compensation prediction of the video signal 321outputted from the memory circuit 301 for outputting the predictionpicture 323.

[0017] In the beginning, in the case where the picture 322 coded anddecoded as described above is either an I picture or a P picture, thispicture 322 is stored in the frame memory 404 a or the frame memory 404b for coding the subsequent picture. At this time, the switcher 403 isswitched so that the frame memory out of the two frame memories 404 aand 404 b which is renewed prior to the other in time is selected.However, when the decoded picture 322 is a B picture, writing is notperformed at the frame memory 404 a and the frame memory 404 b

[0018] For example, when 1st and 2nd pictures in FIG. 7 are coded bysuch switching of the switcher 403, the 0th P picture and the 3rd Ipicture are stored in the frame memory 404 a and frame memory 404 b,respectively. Further, when the 6th P picture is coded and decoded, theframe memory 404 a is rewritten into the decoded picture of the 6th Ppicture.

[0019] Consequently, when the 4th and the 5th B pictures are coded, the6th P picture and the 3rd I picture are stored in the frame memories 404a and 404 b, respectively. Further, when the 9th P picture is coded anddecoded, the frame memory 404 b is rewritten into the decoded picture ofthe 9th P picture. As a consequence, when the 7th B picture and the 8thB picture are coded, the 6th P picture and the 9th P picture are storedin the frame memories 404 a and 404 b, respectively.

[0020] When the video signal 321 outputted from the memory circuit 301is inputted to the motion compensation predicting circuit 310, themotion vector detecting circuits 405 a and 405 b detect a motion vectoron the basis of a reference picture stored in the frame memories 404 aand 404 b and output a motion compensation prediction picture. In otherwords, the video signal 321 is divided into a plurality of blocks. Thena block is selected so that the prediction distortion becomes thesmallest in the reference picture with respect to each block. Then therelative position of the block is outputted as the motion block, and atthe same time this block is outputted as the motion compensationprediction picture.

[0021] In the meantime, the prediction mode selector 406 selects apicture where the prediction distortion is the smallest out of twomotion compensation prediction pictures outputted from the motion vectordetecting circuits 405 a and 405 b or an average picture thereof. Then,the selected picture is outputted as a predicted picture. At this time,when the video signal 321 is not a B picture, the motion compensationprediction picture is always selected and outputted which corresponds tothe reference picture which is inputted prior to the other before intime. Further, the prediction mode selector 406 selects either coding inpictures in which prediction is not performed or prediction coding bythe selected prediction picture in such a manner that the selectedcoding has a better coding efficiency.

[0022] At this time, when the video signal 321 is an I picture, thecoding in pictures is always selected. When the coding in pictures isselected, a signal representative of the coding in the picture mode isoutputted as a prediction mode. In the meantime, when the predictioncoding between pictures is selected, a signal representative of aselected prediction picture is outputted as a prediction mode. Theswitcher 407 outputs a zero signal when the prediction mode outputtedfrom the prediction mode selector 406 is a mode of coding in pictures.If the prediction mode is not the mode of coding in pictures, theprediction mode selector 406 outputs the prediction picture.

[0023] It follows from the aforementioned fact that when the videosignal 321 outputted from the memory circuit 301 is an I picture, themotion compensation predicting circuit 310 always outputs the zerosignal as a prediction picture 323, the I picture is not subjected tothe inter-frame prediction but to the intra-frame conversion coding. Inthe meantime, when the video signal outputted from the memory circuit301 is the 6th P picture in FIG. 6, the motion compensation predictioncircuit 310 performs the motion compensation prediction from the 3rd Ipicture in FIG. 8 and outputs the prediction picture 323. Further, whenthe video signal 321 outputted from the memory circuit 301 is the 4th Bpicture shown in FIG. 6, the motion compensation prediction circuit 310performs the motion compensation prediction from the 3rd I picture andthe 6th P picture shown in FIG. 6 and outputs the prediction picture323.

[0024] Subsequently, an operation of the transmission buffer 306 will beexplained. The transmission buffer 306 converts video datavariable-length coded by the variable-length encoder 305 into abitstream of the MPEG video signal. Here, the stream of the MPEG has asix layer structure shown in FIG. 5. Header information which is anidentification code is added for a sequence layer 621, a GOP layer 622,a picture layer 623, a slice layer 624 and a block layer 626 toconstitute the layer structure.

[0025] Further, the transmission buffer 306 decomposes a bitstream of avideo signal and a bitstream of an audio signal into a plurality ofpackets respectively so that these packets are multiplexed including asynchronization signal thereby constituting a system stream of aMPEG2-PS (program stream). Here, the MPEG2-PS consists of a pack layerand a packet layer as shown in FIG. 8. Then the header information isadded to the packet layer and the pack layer. In the conventionalexample, a system stream is constituted so that data of one GOP portionof the video data is included.

[0026] Here, the pack layer has a structure in which the packet layer isbound at the upper layer of the packet layer. Each packet layer whichconstitutes the pack layer is referred to as a PES packet. In addition,header information of the pack layer shown in FIG. 8 includes anidentification signal of a pack and a synchronous signal whichconstitutes a basis of a video signal and an audio signal.

[0027] In the meantime, in the packet which constitutes the packetlayer, three kinds of PES packets exist as shown in FIG. 9. Here, asecond stage packet shown in FIG. 9 is a video/audio/private 1 packetwherein a code for identifying the front of the packet and time stampinformation or the like (PTS and DTS) needed at the time of decodingeach packet as header information are added before the packet data.However, the time stamp information PTS is a time control information ofthe reproduction output and is information for controlling a decodingorder of data stream of each packet at the time of reproduction.Further, DTS is time control information at the start of decoding and isinformation for controlling the transmission order of decoding data.

[0028] The third stage packet shown in FIG. 9 is a private 2 packetwhere user data is written. Further, the lowest stage packet is apadding packet where all the packet data is masked with “1” . The headerinformation in the private 2 packet and padding packet is constituted ofa start code of a packet and a packet length.

[0029] As described above, the video data and audio data items areconverted into a system stream of the MPEG2-PS by the transmissionbuffer 306 and is converted for each of the frame sectors. Thisinformation is subjected to error correction processing, and at the sametime, the information is modulated to minimize the interference betweencodes on the disc and is recorded on the optical disc 212. At this time,for example, data amount for each of the GOP unit is set to anapproximately the same amount. Then, it is apparent that the edition foreach of the GOP unit can be made by distributing the data into sectorswhich are equal to integer times of the frame cycle.

[0030] Subsequently, an operation at the time of playback will beexplained. At the time of the playback, the video information recordedon the optical disc 212 is amplified with the playback amplifier 213.After the information is restored to digital data at the demodulator 214and the error correction decoder 215 followed by being restored as pureoriginal video data free of data such as an address and a parity at theframe sector inverse converting circuit 216. Then, the data is inputtedinto the data extending circuit 217 which has a structure shown in FIG.4. The system stream which consists of a MPEG2-PS is inputted to thetransmission buffer 501.

[0031] At the transmission buffer 501, the system stream which isinputted is decomposed into a pack unit. After that, each PES packet isdecomposed in accordance with the header information herebyreconstructing the bitstream of the video data and audio data which isdecomposed in the PES packet unit. Further, with respect to the videodata, the stream is decomposed to the block layer shown in FIG. 5 sothat the block data and the motion vector data is decomposed andoutputted.

[0032] The block data outputted from the transmission buffer 501 isinputted in accordance with the variable-length decoder 502 so that thevariable-length data becomes a fixed length data, inversely quantizedand is subjected to the inverse DCT to be outputted to the adder 506. Inthe meantime, the prediction data decoding circuit 505 decodes theprediction picture in accordance with the motion vector outputted fromthe transmission buffer 501 to be outputted to the adder 506.

[0033] In this case, the prediction data decoding circuit 505, like themotion compensation predicting circuit 310, provides a frame memory forstoring the I picture and P picture data which is decoded by the adder506. Incidentally, with respect to a method for renewing the referencepicture data an explanation will be omitted because the method is thesame as the case of coding the data.

[0034] The adder 506 adds the output of the prediction data decodingcircuit 505 and the output of the inverse DCT circuit 504 to beoutputted to the memory circuit 507. Here, at the time of coding thedata, the frame is rearranged in accordance with the order of coding thedata as shown in FIG. 7 with respect to the video signals which arecontinuous in time. Therefore, in the memory circuit 507, the datainputted in the order shown in FIG. 7B is rearranged so that the picturedata continues in time and is outputted to the D/A converter 218.

[0035] Subsequently, the picture retrieval and the high speed playbackthereof will be shown in the case where data with such a codingstructure is recorded on the optical disc. In the case where the codingstructure shown in FIG. 6 is provided, the high speed playback of thepicture can be performed when the data is played back in the unit of theI picture. In this case, the track jump is performed immediately afterthe I picture is played back. Then, the following or the preceding GOPis accessed so that the I picture is played back there. In the caseshown in FIG. 6, the high speed feeding playback and rewinding playbackcan be actualized by repeating such an operation.

[0036] However, since this GOP rate is a variable bit rate, it isimpossible to recognize at all where the front of the following GOP islocated. Consequently, the optical head is allowed to appropriately jumpto locate the front of the GOP. Thus, it is impossible to determinewhich track should be accessed.

[0037] In addition, the I picture has a large amount of data. Thus, whenonly the I picture is played back in a continuous manners like a specialplayback, the picture cannot be played back at a frequency of 30 Hz likea normal animated picture because of a limit on the reading speed fromthe disc. Even when the optical head jumps after the completion of the Ipicture playback, the intermission for the renewal to the following Ipicture becomes longer so that the operation lacks in smoothness.

[0038] The conventional digital video signal record and playback device,is constituted in the aforementioned manner. In the case where a highspeed playback is performed at several times speed by using the Ipicture and the P picture, the I picture data and the P picture data isread after the front of the GOP is detected from bitstreams which arerecorded on a recording medium or the like such as an optical disc orthe like. Consequently, in the case where the data amount of the Ipicture and the P picture become very large, or in the case where ittakes much time to search the front of the GOP, time for reading thedata from the recording medium becomes insufficient. Thus there arises aproblem in that the data all the I picture and the P picture cannot beread so that the high speed playback cannot be realized.

[0039] In the conventional digital video signal record and playbackdevice, it takes much time to input I picture data which has a largeamount of data even when the high speed playback is performed only byusing the I picture. Consequently the special playback which surpassestens of times cannot be realized. In this case, a higher speed specialplayback can be realized by playing back one I picture for several GOP.There is a problem in that the interval for the renewal of played backpicture will be prolonged so that the content of the picture will becomevague.

[0040] Since the conventional video signal record and playback device iscoded as described above, only the I picture having a large amount ofdata is decoded at the time of the skip search (watching data through arapid playback). Consequently, the optical head is allowed to jumpwithout playing back data sufficient for the decoding. Otherwise, when asufficient amount of data is played back, the time for the playback ofdata is long, the destination to which the GOP is to jump must be set toa considerably far place causing a problem that the number of scenesoutputted to the screen becomes few.

[0041] In addition, since the sector address of the following GOP cannotbe recognized because of the variable rate, it is not verified whetheror not the front of the GOP is located at the track to which the jump ismade. Consequently, there arises a problem in that a plurality of discrotation are required to locate the front of the COP at the track ofdestination and the number of scenes which are outputted to the screenbecomes much fewer at the time of the special playback. Further, therearises a problem in that if the sector address can be recognized, nomeans is available for judging to what extent data can be played backfor the optical head jump with the result that no judgement can be madewithout passing through the video decoder, and the efficiency at whichthe optical head jumps is lowered.

[0042] As other conventional digital video signal record and playbackdevices, some devices are disclosed in, for example, Japanese PatentApplication Laid-Open No. HEI 6-98314 (1994), Japanese PatentApplication Laid-Open No. HEI 6-78289 (1994) and the like. One exampleis shown in FIG. 10. In FIG. 10, reference numeral 775 denotes a videosignal generator such as a camera, a VTR or the like, 776 an audiosignal generator such as a microphone, a VTR or the like, 762 a videosignal encoder, 763 an audio signal encoder, 777 a system layerbitstream generator, 778 an error correction coder, 779 a digitalmodulator, 780 an optical disc, 756 a playback amplifier, 786 adetector, 781 a digital demodulator, 758 an error corrector, 759 asystem stream processor, 782 a video signal decoder, 783 an audio signaldecoder, 784 a monitor and 785 a speaker.

[0043] Currently, optical discs generally used have a diameter of 120mm. These optical discs are normally capable of recording 600 M byte ormore data. Quite recently, these optical discs are capable of recordingvideo signal and an audio signal for 74 minutes at a data rate of about1.2 Mbps. At the time of data recording, a video signal is inputted tothe video signal encoder 762 from the video signal generator 775 forencoding the video signal. From the audio signal generator 776, theaudio signal is inputted to the audio signal encoder 763 for encodingthe audio signal. The process for multiplexing the header or the like tothese two encoded signals is carried out by the system layer bitstreamgenerator 777. After the error correction code is appended by the errorcorrection coder 778, the error correction signal is digitally modulatedwith a digital modulator 779 thereby generating a bitstream forrecording. This bitstream creates a mother disc with a recording means(not shown), and the content of the mother disc is copied to the opticaldisc 780 with the result that a commercially available video softwaredisc is prepared.

[0044] In a playback device for users, a signal obtained from the videosoftware disc by the optical disc is amplified with the playbackamplifier 756 to input a playback signal to the detector 786. After thisplayback signal is detected with the detector 786, the digitaldemodulator 781 digitally demodulates the signal to correct errors withan error corrector 758. After this, the video signal area is extractedfrom the signal which has been error corrected, and this extracted datais decoded at the video signal decoder 782 and outputted together withthe audio signal decoded by the audio signal decoder 783 to the monitor784 and the speaker 785 respectively.

[0045] A typical method for coding this video signal is an MPEG 1 and anMPEG 2 referred to as an MPEG (Moving Picture Experts Group) methodwhich is an international standard coding method. A concrete example ofcoding method will be explained with respect to an example of MPEG 2.

[0046]FIG. 11 shows a block diagram of an video signal coding part in aconventional digital signal record and playback device for explainingthe MPEG2 coding method. FIG. 12 is a block diagram of an video signaldecoding unit in a conventional digital signal record and playbackdevice for explaining a decoding method. Further, FIG. 13 is a viewshowing a concept of the mobile picture processing for the video signalcoding in the conventional digital signal record and playback device forexplaining the grouping of mobile pictures according to the codingmethod of the MPEG 2. Referring to FIG. 13, IBBPBBP designates - - - , Ian I picture, B a B picture and P a P picture. For example, in FIG. 13A,mobile pictures from I to the one immediately before the appearance ofanother I are grouped in a definite number of frames. The number offrames of the pictures which constitute this group is normally 15 framesin many cases. However, the number is not limited to any specificnumber.

[0047] The GOP, a group of pictures which constitutes this groupincludes at least one frame of I picture which can be decoded completelyin one frame. The GOP also includes a P picture coded through the motioncompensation prediction by one direction prediction of the time systemon the basis of the I picture and a B picture coded by both directionprediction of the time system on the basis of the I picture and the Ppicture. Incidentally, the arrows in FIGS. 13A and 13B representprediction relations.

[0048] In other words, the B picture can be coded and decoded only afterthe I picture and the P picture are prepared. The initial P picture inthe GOP can be coded and decoded after the I picture before the Ppicture is prepared. The second P picture and P picture after that canbe coded and decoded when the P picture immediately before the P pictureis prepared. Consequently, in the absence of the I picture, either the Por B pictures cannot be coded and decoded.

[0049] Referring to FIG. 11, reference numeral 787 denotes a picturerearranger, 788 a scan converter,789 an encoder buffer, 790 a modedeterminer, 702 a motion vector detector, 706 a subtracter, and 708 aDCT circuit which has a field memory, a frame memory, and DCTcalculator. Reference numeral 710 denotes a quantizer, 714 an inversequantizer, 716 an inverse DCT circuit, 718 an adder, 720 an imagememory, 722 a rate controller and 726 a variable-length encoder.

[0050] Referring to FIG. 12, reference numeral 733 denotes avariable-length decoder, 736 an inverse DCT circuit, 737 an imagememory, 788 an adder, 739 an inverse scan converter. Incidentally, themotion vector detector 702 and the mode determiner 790 combines togetherto represent a motion vector detecting unit.

[0051] Subsequently, on the basis of FIGS. 11 though 13, an operation ofa digital video signal record and playback device will be explained.Referring to FIG. 11, the picture rearranger 787 rearranges pictures forcoding in an order shown in FIG. 13. Then the scan converter 788converts the scan from the raster scan to the block scan. This picturerearrangement and the conversion processing from the raster scan to theblock scan are generally referred to as preprocessing. The picturerearranger 787 and the scan converter 788 are generally referred to aspreprocessor. The inputted picture data is subjected to block scan inthe order of encoding. When the picture is an I picture, the picturepasses through the subtracter 706. When the picture is a P picture or aB picture, the picture is subtracted with the reference picture and thesubtracter 706.

[0052] At this time, the motion vector detector 702 determines themotion direction and the motion quantity (the input of the originalpicture to this motion vector detector 702 may be a picture after thepicture rearrangement or a picture after the block scan as an originalpicture, but the circuit size is smaller in the latter case. Further,the reference picture must be inputted from the image memory 720 but thereference arrow in the drawing is omitted) with the result that a signalin the area in consideration of the portion of the direction andquantity from the image memory 720 may be read. At this time, the modedeterminer 790 determines whether both direction prediction is used or aone direction prediction may be used.

[0053] The substraction with the reference screen in consideration ofthe motion vector is performed at the subtracter 706. Even pictures witha small electric power are constituted so that the coding efficiency isheightened. The output from the subtracter 706 is collected either in aunit of field or in a unit of frame at the DCT circuit 708 to besubjected to a DCT process and converted into data in a frequencycomponent. This data is inputted to the quantizer 710 where the weightis different for each of the frequency. The data is scanned in a zigzagmanner in two dimensions over low frequency components and highfrequency components to be subjected to a run length coding and aHuffman coding.

[0054] This data which has been subjected to the run length coding andHuffman coding is controlled for variable-length coding so that aquantizing table is scaled by using the rate controller 722 to allow thedata to agree with a target code quantity. The data that has beensubjected to variable-length coding is normally outputted via theencoder buffer 789. The quantized data is brought back to the inversequantizer 714 to be brought back to an original picture space data bythe inverse DCT circuit 716 with the result that data which is the sameas the decoded data is obtained by the adder 718 by adding the originalpicture space data to the data referenced by the subtracter 706.

[0055]FIG. 12 shows a schematic block structure of a decoder. Thevariable-length decoder 733 decodes picture data including headerinformation such as the motion vector, the coding mode, the picture modeor the like. After this decoded data is quantized, the inverse DCTcircuit 736 performs the inverse DCT calculation (incidentally, in FIG.12, the inverse quantizer located in the front stage of the inverse DCTcircuit 736 is omitted). By referring to the picture data from the imagememory 737 in consideration of the motion vector, the motioncompensation prediction is decoded by adding the picture data that hasbeen referred to with the data after the inverse DCT by the adder 738.This data is converted into a raster scan with the inverse scanconverter 739 to obtain and output an interlace picture.

[0056] Further, in accordance with the variable transmission rate discsystem introduced in “the variable transmission rate disc system and thecode quantity control method” in a publication of Mr. Sugiyama et al, atthe 1994 annual meeting of the Television Society, a proposal is made ona higher quality digital video signal encoding method. This is a methodin which an encoding rate is fixed with one program (for example, afirst set) so that each GOP is set at a rate depending on the difficultyof the design and encoded. FIG. 14 is a block diagram showing a videosignal coding unit in a conventional digital signal record and playbackdevice. In FIG. 14, reference numeral 791 denotes a motion compensationpredictor, 792 a code amount memory, 793 a GOP rate setting unit, 794 acode amount assigning unit, 795 a subtracter, and 796 a code amountcounter and 797 a switch. The GOP rate setting unit 793 shown in FIG. 14is set to change the setting of the quantizing value according to thedifficulty of the design pattern. In other words, while the switch 797is connected to the virtual coding side, the output of thevariable-length encoder 726 is inputted to the code amount counter 796so that the code amount counter 796 counts the code amount to be storedin the code amount memory 792.

[0057] The GOP rate setting unit 793 determines the virtual code amountin the whole one program on the basis of the code amount stored in thiscode amount memory 792 to set and calculate the optimal encoding rate ineach GOP. The code assignment at this time is calculated from the codeamount assigning unit 794 for the preparation of the actual encoding.When the switch 797 is connected to the actual coding side, the codeamount assignment amount and the value of the code amount counter 796are compared so that the switch 797 is operated to control the quantizer710 on the basis of the actual code amount. In this manner, a small codeamount is assigned to an easy design and a large code is assigned to adifficult amount so that the coding difficulty that gradually changes inthe program is absorbed. As a consequence, it has been reported that thepicture quality of what is recorded at a rate of 3 Mbps by using thismethod is approximately the same as the picture quality of what is codedat a rate of 6 Mbps.

[0058] In consideration of the possibility of the skip search in thedigital video signal record and playback device using an optical disc,when the I picture and the P picture are played back for fast rewindingeven when the front of the GOP can be accessed at a high speed, the Ppicture is located at an appropriate position in the GOP so that therearises a need of operating the optical head while searching data on thebitstream. However, such a control cannot be made in time because of thetime constant of a servo such as an actuator or the like. One GOPnormally includes 15 frames of pictures, and in NTSC scanning method,0.5 second is available for finding the front of the GOP. However, inorder to detect the front of a certain GOP, the bitstream requires thereading of ½ or more for reading ⅓ picture at a frame rate even when anattempt is made to read the I picture or the P picture at the time ofthe skip search with the result that the reading speed has to be set to2.5 times faster or even faster than the normal speed when the headmovement time is set to 200 milliseconds. This exceeds the responselimit of the actuator. In a normal playback methods the skip search issubstantially impossible to carry out.

[0059] In accordance with the conventional digital video signal recordand playback device, the signal is coded in this manner. Thus, when anattempt is made to perform the skip search like a video tape recorder, aperfect playback picture cannot be obtained in the case where the datais played back which does not allow obtaining a complete originalpicture from one picture data item like the B picture. Particularly, inthe skip search, jerkiness (unnatural movement) is generated withrespect to the output processing in the unit of frame. When a variablerate recording is performed with a good playback picture quality, therearises a problem in that the difficulty of accessing the front of theGOP itself increases since the position of the front address of the GOPchanges, with the result that a space is formed in a disc area due todisuniform unit of the GOP.

SUMMARY OF THE INVENTION

[0060] An object of the present invention is to provide a digital videosignal record and playback device which is capable of performing aspecial playback by using an I picture with a large data amount andobtaining a playback picture with a good quality, and a method forrecording and playing back the same.

[0061] Another object of the present invention is to provide a digitalvideo signal record and playback device which is capable of performing ahigh speed playback by using an I picture and a P picture with a largedata amount and obtaining a playback picture with a good quality, and amethod for recording and playing back the same.

[0062] Still another object of the invention is to provide a digitalvideo signal record and playback device which is capable of realizing animprovement in the access characteristics of the GOP under thepresupposition of adopting the coding of a variable bit rate whileobtaining a favorable skip search, and a method for recording andplaying back the same.

[0063] Further another object of the invention is to provide a digitalvideo signal record and playback device which is capable of realizing animprovement in the access characteristics of the GOP and an effectiveuse of space area on a storing medium under the presupposition ofadopting the variable rate coding while performing a skip search, and amethod for recording and playing back the same.

[0064] With the digital video signal record and playback device of thepresent invention, when the video signal is recorded in the unit of GOP,one frame is divided into n areas with respect to the I picture so thateach area is coded and recorded at the front of one GOP in order fromthe area located at the central part of the screen. At the same time,the address information of each area of the I picture is simultaneouslyrecorded as header information. At the time of the special playback,only the data of the I picture in the area located at the central partof the screen is read, and a special playback picture is outputted bymasking a definite value of data with respect to the area where the datais not read. Consequently, compared with the case where all the Ipictures having a great amount of data are played back, a specialplayback can be realized at a faster speed.

[0065] In the aforementioned video signal record and playback device,special playback pictures are outputted by extending the central areathat is read over the whole screen. Consequently, since the data at thecenter portion of the screen is extended to synthesize the playbackpicture, the area in which data cannot be read becomes inconspicuous andthe played back picture becomes favorable to watch.

[0066] With the digital video signal record and playback device of thepresent invention, the video signal is recorded in the unit of GOP, andone frame is divided into n areas with respect to the I picture so thateach area is coded and recorded at the front of one GOP in order fromthe central part of the screen. When the video signal is read and playedback from a recording medium such as an optical disc where the addressinformation of each area in the I picture is simultaneously recorded asheader information, at the time of the special playback only the data ofthe I picture in the area located at the central part of the screen isread. With respect to an area where the data is not read, the specialplayback picture is outputted by masking the data to a definite value.Consequently, compared with the case where all the I pictures are playedback, the special playback can be realized at a faster speed.

[0067] In the aforementioned digital video signal record and playbackdevice, special playback pictures are outputted by extending the readcentral part of the area over the whole screen. Consequently, the areain which data cannot be read becomes inconspicuous and the playbackpicture becomes favorable to watch.

[0068] With another digital video signal playback device of the presentinvention, when the video signal is recorded in the unit of GOP, oneframe is divided into n areas so that each area is coded and is recordedin order from an area located at the central part of the screen at thefront of the one GOP. At the same time, the address information of eacharea of the I picture is simultaneously recorded as header information.At the time of the special playback, only the data of the I picture isread in the unit of area and is outputted as a playback picture. In thecase where all the areas in the I picture cannot be read during adefinite time, the special playback picture is outputted byinterpolating the picture with the data of the preceding screen.Consequently, the area located at the central part of the screen isgiven a priority to be played back with the result that the interpolatedplayback picture becomes favorable to watch.

[0069] With still another digital video signal record and playbackdevice of the present invention, when the video data is recorded in theunit of GOP, one frame is divided into n areas with respect to the Ipicture so that each area is coded and recorded in order from thecentral part of the screen at the front of the one GOP. At the sametime, the address information of each area of the I picture issimultaneously recorded as header information. At the time of thespecial playback, only the data of the I picture is read in the unit ofareas and regions in the areas 1, 2, - - - n are read one by one fromconsecutive n I pictures with the result that pictures for one screenportion is synthesized and is outputted as a playback picture. When allthe areas of the I picture cannot be read in a definite time, thespecial playback picture is outputted by interpolating the picture withthe preceding screen data. Consequently, the area located in the centralpart of the screen is given a priority to be reproduced. Since onescreen is synthesized with n I pictures, the interpolated playbackpicture becomes inconspicuous.

[0070] With still another digital video signal record and playbackdevice of the present invention, when the video picture is recorded inthe unit of GOP, one frame is divided into n areas with respect to the Ipicture so that each area is coded. When the I picture is recorded atthe front of one GOP in summary for each area, the position of the areawhich is initially recorded in the unit of GOP is scrolled forrecording. At the same time, the address information of each area in theI picture is simultaneously recorded as header information. At the timeof the special playback, only the data of the I picture is read in theunit of area and is outputted as a playback picture. In the case whereall the I pictures can not be read in a definite time, the specialplayback picture is outputted by interpolating the picture with data ofthe preceding screen. Consequently, the position of the area is scrolledin the unit of GOP, one screen can be played back in an even manner.

[0071] With still another digital video signal record and playbackdevice of the present invention, when the video data is recorded in theunit of GOP unit, one frame is divided into n areas with respect to theI picture so that each area is coded, is divided into an errorcorrection block unit, and is recorded in order from the area located inthe central part of the screen at the front of the one GOP. At the sametime, the address information of each area of the I picture issimultaneously recorded as header information. At the time of thespecial playback, only the data of the I picture is read in the unit oferror correction block and is outputted as a playback picture. In thecase where all the I picture cannot be read in a definite time, thespecial playback picture is outputted by interpolating the picture withthe data of the preceding screen. Consequently, since the area locatedat the central part of the screen is given a priority to the playback,the playback picture becomes favorable to watch.

[0072] With still another digital video signal record and playbackdevice of the present invention, when the picture data is recorded inthe unit of GOP, one frame is divided into n areas with respect to the Ipicture and the P picture so that each area is coded and the arealocated in the central part of the screen is recorded in order from thearea located in the center at the front of the one GOP. At the sametime, the address information of each area of the I picture and the Ppicture is simultaneously recorded as header information. At the time ofthe special playback, the data of the I picture and the P picture areread in the unit of area and is outputted as a playback picture. In thecase where all the areas of the I picture or the P picture cannot beread within a definite time, the special playback picture is outputtedby interpolating the picture with the data of the preceding screen.Consequently, since the area located at the central part of the screenis given a priority in playback, interpolated playback picture becomesfavorable to watch.

[0073] With still another digital video signal record and playbackdevice of the present invention, when the video signal is recorded inthe unit of GOP, one frame is divided into n areas with respect to the Ipicture and the P picture so that each area is encoded and is recordedin order from an area located at the central part of the screen at thefront of one GOP. At the same time, the address information of each areaof the I picture is simultaneously recorded as header information. Atthe time of the special playback, only the data of the I picture and theP picture are read in the unit of area, and regions of areas 1, 2, - - -, n are read from continuous n I pictures and P pictures to synthesize apicture of one screen portion and is outputted as a playback picture. Inthe case where all the areas of the I picture or the P picture cannot beread within a definite time, the special playback picture is outputtedby interpolating the picture with the data of the preceding screen.consequently, since the area located at the central part of the screenis given a priority in playback, interpolated playback picture becomesinconspicuous.

[0074] With still another digital video signal record and playbackdevice of the present invention, when the video signal is recorded inthe unit of GOP, one frame is divided into n areas with respect to the Ipicture and the P picture so that each area is encoded in the unit offrame. When the divided frame is fixed for each area at the front of oneGOP and is recorded, the position of the area which is initiallyrecorded in the unit of frame is scrolled. At the same time, the addressinformation of each area in the I picture is simultaneously recorded asheader information. At the time of the special playback, only the dataof the I picture is read in the unit of area and is outputted as aplayback picture. In the case where all the I pictures can not be readin a definite time, the special playback picture is outputted byinterpolating the picture with data of the preceding screen.Consequently, the order in which the area of the I picture and the Ppicture is recorded is scrolled in the unit of GOP, a playback picturefor one screen portion can be played back in an even manner.

[0075] With still another digital video signal record and playbackdevice of the present invention, when the video signal is recorded inthe unit of GOP unit, one frame is divided into n areas with respect tothe I picture and the P picture so that each area is encoded and isdivided in the error correction block unit. Then the divided frame isrecorded in order from an area located at the central part of the screenat the front of the one GOP. At the same time, the address informationof each area of the I picture is simultaneously recorded as headerinformation. At the time of the special playback, only the data of the Ipicture is read in the unit of error correction and is outputted as aplayback picture. In the case where all the I pictures cannot be readwithin a definite time, the special playback picture is outputted byinterpolating the picture with the data of the preceding screen.Consequently, since the area located at the central part of the screenis given a priority in playback, interpolated playback picture becomesfavorable to watch.

[0076] In accordance with the digital video signal playback method(device), at least the I picture which is subjected to the intra-framecoding is divided depending on the frequency area, quantizing level orspace resolution so that a bitstream of video data is constitutedwherein the data more important as a picture out of data divided asleast with respect to the I picture is arranged at the front. Then theaddress information of the divided data is arranged as headerinformation at the front of the bitstream of the video data toconstitute a packet. The data recorded on the recording medium isrearranged at the time of the normal playback in the data order beforedividing the data in accordance with the header information in thepacket to be outputted. At the time of the special playback, dataarranged at the front is decoded and outputted for the special playback.Consequently, the data decreases which is to be accessed at the time ofthe special playback by dividing data depending on the frequency area,quantizing level or the space resolution with the result that a smoothspecial playback picture can be obtained. Further, since the address ofthe divided data is recorded as header information of the system stream,the number of bytes that should be instantly played back at the time ofthe playback can be known with the result that the optical head caneffectively jump at the time of the special playback. Further, at thetime of the normal playback, the data is rearranged on the basis of theaddress with the result that disadvantage resulting from the division ofdata can be prevented when played back.

[0077] In accordance with the digital video signal record and playbackmethod (device), at least the I picture which is subjected to theintra-frame coding is divided depending on the frequency area, thequantizing level and the space resolution, so that a bitstream of videodata is constituted wherein the data more important as a picture out ofdata divided as least with respect to the I picture is arranged at thefront. Then the address information of the divided data is arranged asheader information at the front of the bitstream of the video data toconstitute a packet. The data recorded on the recording medium isrearranged at the time of the normal playback in the data order beforedividing the data in accordance with the header information in thepacket to be outputted. At the time of the special playback, dataarranged at the front is decoded and outputted for the special playback.Consequently, the data decreases which is to be accessed at the time ofthe special playback by dividing data depending on the frequency area,quantizing level or the space resolution with the result that a smoothspecial playback picture can be obtained. Further, since the address ofthe divided data is recorded as header information of the system stream,the number of bytes that should be instantly played back at the time ofthe playback can be known with the result that the optical head caneffectively jump at the time of the special playback. Further, at thetime of the normal playback, the data is rearranged on the basis of theaddress with the result that disadvantage resulting from the division ofdata can be prevented when recorded and played back.

[0078] In accordance with another digital video signal record andplayback method (device), at least the I picture which is subjected tothe intra-frame coding at the time of recording is divided into n areas(n>1) so that the I picture divided into n areas is rearranged in theunit of area so that a bitstream of video data is constituted whereinthe area located at the center on the screen is arranged at the front.Then, the address information of the I picture divided into n areas isarranged at the front of the bitstream of data to constitute a packetand is recorded on the recording medium. At the time of the normalplayback, the data of the I picture is rearranged in the unit of areaand is outputted in accordance with the header information arranged atthe front of the packet. At the time of the special playback, thespecial playback can be performed by outputting only the data of the Ipicture that can be read in a definite time from the front of thepacket. Consequently, the data that should be accessed at the time ofthe special playback decreases by dividing data in the area of thescreen at the time of recording. Since the address of the divided datais recorded as header information of the system stream, the number ofbytes that should be instantly played back at the time of the playbackcan be known with the result that the optical head can effectively jumpat the time of the special playback the address jump can be performed ina certain time unit. Further, at the time of the normal playback, thedata is rearranged on the basis of the address with the result thatdisadvantage resulting from the division of data can be prevented whenrecorded and played back.

[0079] In accordance with another digital video signal record andplayback method (device), at least the I picture data which is subjectedto the intra-frame coding is divided into n areas (n>1) so that the Ipicture divided into n areas is rearranged in the unit of area so that abitstream of video data is constituted wherein the area located at thecenter on the screen is arranged at the front. Then, the addressinformation of the I picture divided into n areas is arranged at thefront of the bitstream of video data as header information to constitutea packet. At the time of the normal playback, the I picture datarearranged for each area in accordance with header information arrangedat the front of the packet is rearranged in the area unit and isoutputted from the recording medium on which the data is recorded. Atthe time of the special playback, the special playback is performed byoutputting only the data which can be read in a definite time.Consequently, the address jump can be performed in a certain time unitat the time of the special playback by dividing the data in the area onthe screen with result that the data to be addressed at the time of thespecial playback decreases. Further, since the address of the divideddata is recorded as header information to the system stream, the numberof bytes that should be played back can be instantly detected at thetime of the playback with the result that the jump of the optical headat the time of the special playback can be efficiently performed.Further, since the data is rearranged on the basis of the address at thetime of the normal playback, the data can be played back without causingthe disadvantage resulting from the data division.

[0080] In accordance with still another digital video signal record andplayback method (device), at least the I picture which is subjected tothe intra-frame coding at the time of recording are divided with the lowfrequency area, the high frequency area, the quantizing level and thespace resolution with the result that the basic data out of the dividedI picture are rearranged in the unit of each area on the screen toconstitute a bitstream of the video data where the area located at thecentral part of the screen in the I picture is arranged at the front.The divided areas, the data division, and the address information of thepicture is arranged at the front of the bitstream of the video data asheader information to constitute a packet and is recorded on a recordingmedium. At the time of the normal playback, the data is rearranged inthe unit of area in accordance with the header information which isarranged at the front part of the packet and the data is outputted. Thedivided data is rearranged in the order of the original data. At thetime of the special playback, only the data of the I picture which canbe read in a definite time from the front of the packet is outputted forperforming a special playback. Consequently, at the time of therecording, the data is divided depending on the frequency, thequantization and the space resolution, and is divided in the unit ofarea on the screen. As a consequence, at the time of the specialplayback, the data to be accessed decreases so that a smooth specialplayback can be obtained by gradually decreasing the data amount to beaccessed at the time of the special playback. Further, since the addressof the divided data is recorded as header information and the number ofbytes that should be played back can be instantly detected at the timeof the playback, the jump of the optical head at the time of the specialplayback can be efficiently performed. Further, regarding the datadivided by a plurality of dividing means, the amount of data to be readcan be adjusted in accordance with the special playback speed to copewith a wide scope of the special playback speed. Further, since the datais rearranged on the basis of the address at the time of the normalplayback, the data can be played back without causing the disadvantageresulting from the data division.

[0081] In accordance with still another digital video signal playbackmethod (device), at least the I picture which is subjected to theintra-frame coding are divided in accordance with the low frequencyarea, the high frequency area, the quantizing level or the spaceresolution with the result that the basic data out of the divided Ipicture is rearranged in each area on the screen to constitute abitstream of the video data where the area located at the central partof the screen in the I picture is arranged at the front. The dividedareas, the data division, and the address information of the picture isarranged at the front of the bitstream of the video data as headerinformation to constitute a packet and is recorded on a recordingmedium, from which the data is outputted at the time of the normalplayback by rearranging the data in the unit of area in accordance withthe header information arranged at the front part of the packet. Thedivided data is rearranged in the order of the original data. At thetime of the special playback, only the data of the I picture which canbe read in a definite time from the front of the packet is outputted forperforming a special playback. Consequently, the data is divideddepending on frequency, quantization and space resolution, and isdivided in the unit of area on the screen. As a consequence, the data tobe accessed at the time of special playback is decreased by dividing thedata in the unit of area on the screen. Further, since the address ofdivided data is recorded as header information and the number of bytesthat should be played back is instantly detected at the time of theplayback, the jump of the optical head at the time of the specialplayback can be efficiently performed. Further, regarding the datadivided by a plurality of dividing means, the amount of the data to beread can be adjusted in accordance with the special playback speed tocope with a wide scope of the special playback speed. Further, since thedata is rearranged on the basis of the address at the time of the normalplayback, the data can be played back without causing the disadvantageresulting from the data division.

[0082] In accordance with still another digital video signal record andplayback method (device) (or a digital video signal playback method(device)), only the area that is located at the central part of thescreen of the I picture is read. With respect to the data in the areawhich is not read, the playback picture is synthesized by masking thedata to a definite value. Consequently, compared with the case where allthe I picture which has a large amount of data is played back, thespecial playback can be realized at a higher speed.

[0083] In accordance with still another digital video signal record andplayback method (device) (or a digital video signal playback method(device), only the area that is located at the central part of thescreen of the I picture is read. The playback picture is synthesized byextending the read-out area over the whole screen. Consequently,compared with the case where the whole I picture having a large dataamount is played back, the special playback can be realized at a higherspeed with the result that the area where the data cannot be readbecomes inconspicuous.

[0084] The digital video signal record device of the present inventionincludes first coding means for coding a video signal comprising a codedpicture including at least a picture subjected to the intra-frame codingout of the digital video signal coded by using the motion compensationprediction and the orthogonal transform, second coding means for codinga residual component through coding using the first coding means outputof the video signal, data arrangement means for arranging each of theoutput data outputted from the first and the second coding means at apredetermined position in each picture group data for each of thepicture group data. Compared with the case in which the first codingmeans codes all the video signals, the area to be accessed at least isdecreased by coding a basic part of the mobile picture. The secondcoding means codes video information which is not coded with the firstcoding means so that all the video information is coded with two codingmeans. Further, the data arrangement means rearranges data obtained bytwo coding means so that the data is favorable for the access of thehead. Consequently, coding can be made possible so that the amount ofcode that should be accessed at least at the time of the specialplayback is decreased. Thus, the arrangement of data that should beaccessed at least at the time of the special playback can be efficientlyperformed.

[0085] In the aforementioned digital video signal record device, thevideo information is coded which is thinned at a predetermined intervalwith respect to the video picture comprising coded picture including atleast a picture coded in the frame. Consequently, the first coding meanscodes the thinned video picture so that the area to be accessed at leastis decreased. When only the data of the first coding means is accessed,the video picture can be coded so that the scene can be sufficientlyunderstood when the picture is decoded.

[0086] In the aforementioned digital video signal record device, thefirst coding means codes only the low frequency area which isorthogonally converted. The first coding means codes the picture datawhich is partial in terms of frequency so that the area which is to beaccessed at least is decreased. When only the data of the first codingmeans is accessed, the video picture can be coded so that the scene canbe sufficiently understood when the picture is decoded.

[0087] In the aforementioned digital video signal record device, thefirst coding means roughly quantizes on a quantization level to becoded. The first coding means codes the data of the upper bit whichexerts a deep influence on the picture through the rough quantization sothat the area to be accessed at least is decreased to be coded withoutdecreasing the resolution. When only the data of the first coding meansis accessed, the video picture can be coded so that the scene can besufficiently understood when the picture is decoded.

[0088] Another digital video signal record device of the presentinvention extracts data in the low frequency component from a data arrayin which the video signal is segmented by predetermined bits, the videosignal comprising a coded picture including at least a picture subjectedto the intra-frame coding out of the video signal which is coded usingthe motion compensation prediction and the orthogonal transform. The lowfrequency area of the video signal is segmented by segmenting the databy predetermined bits for each block. Consequently, it is easy to limitthe code amount to be within a fixed length. Besides, when the data inthe low frequency area is decoded, the data can be coded so that thecontent of the picture can be roughly understood.

[0089] The digital video signal playback device of the present inventionrearranges data in the low frequency area and data in the high frequencyarea into a predetermined order so that either of the mode for decodingthe rearranged data or the mode for selectively decoding the data in thelow frequency area. At the time of the normal playback, a completedecoded picture can be obtained by connecting two segmented coded data.At the time of the special playback, only the data in the low frequencyarea is decoded. Consequently, data can be decoded depending on theoperation state of the device with the result that a picture can beobtained to an extent that the rough content of the picture can begrasped.

[0090] In the aforementioned digital video signal playback device, whenthe data is decoded in a mode of decoding only the data in the lowfrequency area, only the data that can be decoded is decoded. The datawhich cannot be decoded in the vicinity of the boundary of apredetermined number of bits is discarded so that the data in the highfrequency area is replaced with the fixed value for an inverseorthogonal transform. When the low frequency area out of two segmentedcoded data is decoded at the time of the special playback, only the datathat can be decoded is decoded and the bit that cannot be decoded isdiscarded. The decoding of the abnormal data can be avoided. Withrespect to the remaining high frequency area, the data is replaced withthe fixed value and decoded with the result that a decoded picture canbe obtained free from data distortion.

[0091] Still another digital video signal record device adds an end ofthe block code to a coded data in each block of the video signalcomprising a coded picture including at least a picture subjected to theintra-frame coding out of the coded digital signals by using the motioncompensation prediction and the orthogonal transform when apredetermined number of bits as data in the low frequency area isattained. The aforementioned coded data which exceeds a predeterminednumber of bits is coded as a high frequency region data. Both the lowfrequency area and high frequency area of the block are coded in such amanner that the block is ostensibly terminated in the end of block (EOB)code. Consequently, when only data in the low frequency area is decoded,coded data can be obtained that can be decoded without requiring aredundant circuit such as discarding of the data.

[0092] Still another digital video signal record device of the presentinvention reconstructs data on the basis of the data in the lowfrequency area, the data in the high frequency area and the EOB code.Then, either a mode of decoding the reconstructed data or the mode ofselectively decoding only data in the low frequency area is selected sothat the coded data reconstructed on the basis of the result ofselection is decoded. With respect to the high frequency area, the datais replaced with a fixed value to perform an inverse orthogonaltransform. At the time of the normal playback, a complete decodedpicture is obtained from the coded data segmented by the EOBrespectively can be obtained. At the time of the special playback, onlydata in the low frequency area is decoded out of the coded data so thatboth the normal and special playback modes can be operated depending onthe operation state of the device with the result that a rough picturecan be obtained which allows us to understand the scene. Further, whenthe low frequency area is decoded out of the coded data, the remaininghigh frequency area of the block is replaced with the fixed value and isdecoded with the result that the area can be decoded free from datadistortion. Both the high frequency area and the low frequency area ofthe block can be decoded as if the block is ostensibly ended at the EOB.

[0093] Still another digital video signal record device of the presentinvention includes a low resolution coding means for coding data of thelow resolution component in which pixels are thinned with respect to avideo signal comprising a coded picture including at least a picture inthe frame out of the coded digital picture by using the motioncompensation prediction and the orthogonal transform, differentialcomponent coding means for coding a differential component with thepicture before thinning the pixels by interpolating the output data ofthe low resolution coding means, and information adding means forconstituting data by dividing the output of the low resolution codingmeans and the differential component coding means into predeterminedareas for adding an error correction codes. When the picture datathinned in space is coded so that only this coded data is accessed, thepicture data can be coded so that the scene can be sufficientlyunderstood when the picture is decoded. The decoded data from the lowresolution coding means is interpolated thereby obtaining a differentialcomponent by comparing the picture with the picture before the lowresolution conversion with the result that the picture data of the highresolution portion which cannot be obtained by low resolution codingmeans is coded. Thus the picture information other than the lowresolution degree can be coded.

[0094] Still another digital video signal playback device of the presentinvention synthesizes the data of the low resolution component with thedata of the differential component to be decoded. At the time of thenormal playback, the coded data of the low resolution component and thecoded data of the high resolution component which is the differentialcomponent between the low resolution portion and the data before beingthinned into a low resolution are synthesized so that a picture with acomplete resolution component can be decoded.

[0095] In the aforementioned digital video signal playback device of thepresent invention, a mode of decoding a picture by synthesizing the dataof a low resolution component with the data of the differentialcomponent is switched over with a mode of decoding only the lowresolution component. At the time of the normal playback, a lowresolution coded data segmented into two is synthesized with the codeddata of a high resolution component which is a differential componentbetween data before being thinned to a low resolution and the data ofthe low resolution portion are synthesized so that a picture with acomplete resolution can be decoded. At the time of the special playback,a decoding mode is switched over in accordance with the operating stateof the device so that a rough picture can be decoded by decoding onlythe coded data of low resolution.

[0096] In the aforementioned digital video signal playback device, whenthe low resolution picture is decoded, only the picture interpolatedafter decoding is generated. At the time of the special playback, whenonly the coded data of low resolution is decoded, the video data of thelow resolution component is interpolated to bring back the size of thepicture to the original size thereof.

[0097] Still another digital video signal record device of the presentinvention includes judging means for judging the degree of picturedeterioration at the time of coding and decoding on a basis of themotion compensation prediction and the orthogonal transform, adaptivecoding means for coding a data rate by adaptively changing the rate onthe basis of the judgment output from the judging means, informationadding means for adding an audio signal, additional information such asheader or the like, and error correction code, and a data rate settingmeans for setting a discrete value for the adaptively changed data rate.In the coding means for a variable rate, the rate is limited only to alimited value. Consequently, the data rate information of the GOP (whichcorresponds to the code amount of the GOP) can be represented with asmall number of bits.

[0098] Still another digital video signal record device of the presentinvention includes judging means for judging the degree of picturedeterioration at the time of coding and decoding on the basis of themotion compensation prediction and the orthogonal transform, adaptivecoding means for coding a data rate by adaptively changing the rate onthe basis of the judgment output from the judging means, informationadding means for adding an audio signal, additional information such asheader or the like, and error correction code, wherein the device is soconstituted that data rate information is multiplexed on the head or thelike, or is written in a predetermined area on the recording medium. Thedata rate set information in the case where the picture data is coded ata variable rate is recorded on the recording medium apart from the videodata. Consequently, the data rate information can be read in summary sothat information can be recorded which allows immediate recording of theposition of the predetermined GOP which occupies a disc.

[0099] Still another digital video signal record device includes judgingmeans for judging the degree of picture deterioration at the time ofcoding and decoding on the basis of the motion compensation predictionand the orthogonal transform, information adding means for adding anaudio signal, additional information such as header or the like, anderror correction code, first coding means for coding a video signalthinned at a predetermined interval with respect to a video signalcomprising a coded picture including a picture subjected to theintra-frame coding, second coding means for coding with respect to theremaining component by coding using the first coding means out of thevideo signal, wherein the device is so constituted that the data rate atleast in either of the coding means out of the first or the secondcoding means is adaptively changed and coded on the basis of a judgmentoutput from the judging means. A high quality coding can be realized bythe variable rate. In the GOP in which the rate has largely increased,the video data thinned in space is coded and coding can be performed sothat the area which is accessed at least is decreased.

[0100] Still another digital video signal record device of the presentinvention includes judging means for judging the degree of picturedeterioration at the time of coding and decoding on the basis of themotion compensation prediction and the orthogonal transform, informationadding means for adding an audio signal, additional information such asheader or the like, and error correction code, first coding means forcoding only a low frequency area orthogonally transformed with respectto a video signal comprising a coded picture including a picturesubjected to the intra-frame coding, second coding means for coding withrespect to the remaining component by coding the signal using the firstcoding means out of the video signal, wherein the device is soconstituted that the video signal is coded by adaptively changing thedata rate in at least either of the coding means out of the first codingmeans or the second coding means on the basis of the judgment outputfrom the design judging means. A high quality coding can be realizedwith the variable rate. With the GOP in which the rate has largelyincreased, the video data in a partial frequency area is coded for eachblock, and the coding can be performed so that the area accessed atleast is decreased.

[0101] Still another digital video signal record device includes judgingmeans for judging the degree of picture deterioration at the time ofcoding and decoding on the basis of the motion compensation predictionand the orthogonal transform, information adding means for addingadditional information such as an audio signal, a header or the like andan error correction code, first coding means for coding a video signalthrough a rough quantization on a quantization level with respect to avideo signal comprising a coded picture including a picture subjected tothe intra-frame coding, second coding means for coding with respect tothe remaining component by coding the signal using the first codingmeans out of the video signal, wherein that the video signal is coded byadaptively changing the data rate in at least either of the coding meansout of the first coding means or the second coding means on the basis ofthe judgment output from the design judging means. A high quality codingcan be realized with a variable rate. In the GOP in which the rate haslargely increased by the variable rate, the data in the upper bit whichdeeply affects the picture is coded, and the coding can be performed sothat the area accessed at least is decreased.

[0102] Still another digital video signal playback device of the presentinvention switches over a playback mode between the normal playback modeand the special playback mode thereby extracting data rate information.At the time of the special playback mode, the position of the recordingmedium where data for the special playback exists is calculated on thebasis of the data rate information at the time of the special playbackmode. When the GOP with a different data rate is played back byextracting the data rate information of each GOP, the coded data dividedinto two are synthesized and decoded at the time of the normal playback.At the time of the special playback, the position of the GOP on therecording medium which is to be accessed is calculated. Then, the datato be accessed at least is played back to access the next target GOP. Atthis time, the position information on the recording medium where theGOP to be accessed is calculated to facilitate the special playback andretrieval of a high quality variable rate.

[0103] In the aforementioned digital video signal playback device, ahead position is controlled to a position on the recording mediumdepending on the result of the position calculation and the specialplayback rate. The position information on the disc where the GOP whichconstitutes the access target is calculated on the basis of the specialplayback rate. The position of the optical head can be controlled to theposition of the target GOP depending on the special playback rate sothat a high quality variable rate can be played back in a special modeat variety of speed.

[0104] With still another digital video signal record device of thepresent invention, a code amount is controlled corresponding to an areaassigned to one picture group which is formed by the digital videosignal coded on the basis of the motion compensation prediction and theorthogonal transform, and the device of the present invention includescoding means for coding, code amount comparing means for comparing anoutput from the coding means with a predetermined amount of data, and adata feeding means for embedding superfluous data in a blank area ofpicture groups having the blank areas In the case where the data iscoded and recorded at a variable rate, the access time can be shortenedby locating the GOP at a position wherein the head is easily accessed sothat the data is coded and recorded increasing the read data amount inthe special playback. Further, unnecessary parts such as blank parts onthe disc at that time can be filled as much as possible thereby usingsuch parts for the improvement in the picture quality or contributing tothe extension of the recording time by those parts.

[0105] Still another digital video signal playback device of the presentinvention includes data reconstructing means for reconstructing embeddedvideo signal coded data into original group of pictures, and datadecoding means for decoding data reconstructed by data reconstructingmeans. A coded data in which other GOP data is embedded in a blank partcan be reconstructed so that the data can be decoded without distortion.Further, the data amount still increases at the time of the specialplayback, and a high quality playback picture can be still obtained.

[0106] Still another digital video signal playback device of the presentinvention switches over on the basis of the special playback speed as towhich of the three decoding means, first decoding means for decoding afirst and second coded data and obtaining a playback picture, a seconddecoding means for decoding the first coded data and obtaining theplayback picture which corresponds to the low frequency region of thepicture subjected to the intra-frame coding, the number of pixelsthinned out or a rough quantization, and a third decoding means fordecoding the first coded data and obtaining a playback picturecorresponding to the low frequency region of the intra-frame codedpicture and the inter-frame prediction picture, the number of pixelsthinned out, or the rough quantization. Since the mode is switched overbetween a mode of decoding and displaying only the I picture and themode of displaying the I picture and the P picture, the special playbackof the I picture and the P picture can be realized at a relatively slowspecial playback (for example, a double-speed playback) with the resultthat a fine special playback free from frame jumping can be realizedcompared with the special playback of only the I picture. Further, atthe time of the special playback at a high speed, various playbackspeeds can be treated such as the special playback of the I picture.

[0107] Still another digital video signal playback device of the presentinvention includes video data extracting means for extracting datacorresponding to the video signal from the playback code, picture datadecoding and playback means for decoding and playing back the video dataoutputted from the video data extracting means, and mode switching meansfor switching a normal playback mode, a mode for playing back anddisplaying either an odd number field or an even number field, and amode for displaying either the odd number field or an even number fieldby reversing the field structure thereof. At the time of the specialplayback, the field structure is optimized depending on the mode. At thetime of the reverse playback, the display is given so that the device isoperated in a reverse manner until the field display. At the time of theplayback of the frame jumping such as fast winding or the like, aspecial playback picture can be obtained which is easy to watch byoutputting the same video picture both in the even number field and inthe odd number field to set the number of fields to a definite level.

[0108] The above and further objects and features of the invention willmore fully be apparent from the following detailed description withaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0109]FIG. 1 is a block diagram of a conventional optical disc recordand playback device.

[0110]FIG. 2 is a block diagram of a video signal coding unit in aconventional MPEG.

[0111]FIG. 3 is a block diagram of a conventional motion compensationpredicting circuit.

[0112]FIG. 4 is a block diagram of a video signal decoding unit in theconventional MPEG.

[0113]FIG. 5 is a view showing a data arrangement structure of a videocoding algorithm of the conventional MPEG.

[0114]FIG. 6 is a view showing an example of a GOP structure of a videocoding algorithm of the conventional MPEG.

[0115]FIGS. 7A and 7B are views showing one example of a video bitstreamof the conventional MPEG.

[0116]FIG. 8 is a view showing an example of a system stream in the PSin the conventional MPEG.

[0117]FIG. 9 is a view showing an example of a PES packet stream of theconventional MPEG.

[0118]FIG. 10 is a block diagram of the conventional digital signalrecord and playback device.

[0119]FIG. 11 is a block diagram of a video signal coding unit in theconventional digital video signal record and playback device.

[0120]FIG. 12 is a block diagram of a video signal decoding unit in theconventional digital video signal record and playback device.

[0121]FIGS. 13A and 13B are views illustrating a concept of mobilepicture processing in the conventional digital signal record andplayback device.

[0122]FIG. 14 is a block diagram of a video signal coding unit in theconventional digital signal record and playback device.

[0123]FIG. 15 is a block diagram of a record system in a digital signalrecord and playback device according to embodiment 1.

[0124]FIG. 16 is a block diagram of a playback system in the digitalrecord and playback device according to embodiment 1.

[0125]FIG. 17 is a conceptual view for illustrating macro blocks.

[0126]FIG. 18 is a conceptual view for illustrating a screen division.

[0127]FIG. 19 is a conceptual view for illustrating a data arrangement.

[0128]FIGS. 20A through 20D are conceptual views for illustrating aplayback method in a special playback.

[0129]FIGS. 21A and 21B are conceptual views for a method for performingthe special playback in the case where the data is extended.

[0130]FIG. 22 is a conceptual view for illustrating a screen divisionaccording to embodiment 3.

[0131]FIG. 23 is a conceptual view for illustrating a data arrangementaccording to embodiment 3.

[0132]FIGS. 24A through 24E are conceptual views for illustrating amethod for performing the special playback according to embodiment 3.

[0133]FIGS. 25A and 25B are conceptual view for illustrating an errorcorrection block arrangement according to embodiment 3.

[0134]FIGS. 26A through 26D are conceptual views for illustrating amethod for performing the special playback according to embodiment 4.

[0135]FIGS. 27A through 27F are conceptual views for illustrating amethod for performing the special playback in the case where the datainterpolation in embodiment 4 is performed.

[0136] FIGS. 28 is a conceptual view for illustrating a data arrangementin embodiment 5.

[0137]FIGS. 29A through 29E are conceptual views for illustrating aplayback method in a special playback according to embodiment 5.

[0138]FIG. 30 is a conceptual view for illustrating a data arrangementin embodiment 6.

[0139]FIGS. 31A through 31F are conceptual views for illustrating amethod for performing the special playback in embodiment 6.

[0140]FIGS. 32A and 32B are conceptual views for illustrating an errorcorrection block arrangement in embodiment 6.

[0141]FIGS. 33A through 33G are conceptual views for illustrating aplayback method in embodiment 7.

[0142]FIGS. 34A through 34F are conceptual views for illustrating amethod for performing the special playback in the case where the datainterpolation in embodiment 7 is performed.

[0143]FIG. 35 is a conceptual view for illustrating data arrangement inembodiment 8.

[0144]FIG. 36A through 36F are conceptual views for illustrating amethod for performing the special playback in embodiment 8.

[0145]FIG. 37 is a block diagram of a digital video signal coding unitin embodiment 9.

[0146]FIG. 38 is a view showing a concept of a frequency division inembodiments 9 and 11.

[0147]FIG. 39 is a flowchart of a digital video signal coding processingin embodiment 9.

[0148]FIG. 40 is a view for illustrating a header in a bitstream inembodiment 9.

[0149]FIGS. 41A through 41D are views showing rearrangement of thebitstream in embodiment 9.

[0150]FIG. 42 is a view showing an example of address information of asystem stream in embodiment 9.

[0151]FIG. 43 is a block diagram of a digital video signal decoding unitin embodiment 9.

[0152]FIG. 44 is a view showing a concept of decoding processing inembodiment 9.

[0153]FIG. 45 is a flowchart of decoding processing in embodiment 9.

[0154]FIG. 46 is a block diagram of a digital video signal coding unitin embodiment 10.

[0155]FIG. 47 is a block diagram of a digital video signal decoding unitin embodiment 10.

[0156]FIG. 48 is a view showing an example of an area of a screen inembodiment 10.

[0157]FIG. 49 is a view showing an example of a bitstream when the videodata is rearranged in the unit of area of the screen in embodiment 10.

[0158]FIG. 50 is a flowchart of a digital video signal coding processingin embodiment 10.

[0159] FIG, 51 is a view showing an example of address information of asystem stream in embodiment 10.

[0160]FIG. 52 is a view showing an example of a system stream inembodiment 10.

[0161]FIGS. 53A through 53E are views showing an example of a playbackscreen in which the picture can be played back at the time of theplayback.

[0162]FIGS. 54A through 54E are views showing an example of the playbackscreen in embodiment 10 wherein only the central part of the screen isoutputted at the time of the playback.

[0163]FIGS. 55A and 55B are views showing an example the playback screenin embodiment 10 in which an area in the central part of the screen ismagnified and displayed.

[0164]FIG. 56 is a flowchart of a digital video decoding processing inembodiment 10.

[0165]FIG. 57 is a block diagram of a digital signal coding unit inembodiment 11.

[0166]FIG. 58 is a flowchart of a digital video signal coding processingin embodiment 11.

[0167]FIGS. 59A through 59D are views showing an example of a systemstream in embodiment 11.

[0168]FIG. 60 is a view showing an example of address information of thesystem stream in embodiment 11.

[0169]FIG. 61 is a block diagram of a digital video signal decoding unitin embodiment 11.

[0170]FIG. 62 is a flowchart of a digital video signal decodingprocessing in embodiment 11.

[0171]FIG. 63 is a block diagram of a digital video signal coding unitin embodiment 11.

[0172]FIG. 64 is a view showing a concept of a resolution conversion inembodiment 12 on the screen.

[0173]FIG. 65 is a view illustrating one example of data constitutionresults in embodiments 12, 13 and 14.

[0174]FIG. 66 is a block view of a digital video signal coding unit inembodiment 13.

[0175]FIG. 67 is a view illustrating one example of a data arrangementof a DCT coefficient inside of a DCT block.

[0176]FIG. 68 is a block diagram of a digital video signal coding unitin embodiment 14.

[0177]FIG. 69 is a view illustrating an example of the statisticalamount of coded data in embodiments 12, 13 and 14.

[0178]FIG. 70 is a view showing one example of a processing sequence inembodiments 12, 13 and 14.

[0179]FIGS. 71A through 71D are views illustrating one example ofarrangement outline of a frequency component in a bitstream of the DCTblock in embodiment 15 and in one block.

[0180]FIG. 72A is a block diagram of a digital video signal decodingunit in embodiment 15.

[0181]FIG. 72B is a view illustrating an operation concept of a digitalvideo signal decoding processing in embodiment 15.

[0182]FIG. 73A is a block diagram showing a digital video signal codingunit in embodiment 16.

[0183]FIG. 73B is a view illustrating an operation concept of a digitalvideo signal coding processing in embodiment 16.

[0184]FIG. 74 is a block diagram of a digital video signal decoding unitin embodiment 16.

[0185]FIG. 75 is a block diagram of a digital video signal decoding unitin embodiment 17.

[0186]FIG. 76 is a block diagram of a GOP address generator and a disccontroller in embodiment 18.

[0187]FIG. 77 is a block diagram of a GOP address generator and a disccontroller including a playback processing in embodiment 18.

[0188]FIG. 78 is a block diagram of a digital video signal decoding unitwhen the division by the frequency and the division by the quantizationin embodiment 19 are performed.

[0189]FIG. 79 is a block diagram of the digital video signal decodingunit when the division by the bit length in embodiment 19 is performed.

[0190]FIG. 80 is a block diagram of the digital video signal decodingunit when the division by the resolution in embodiment 19 is performed.

[0191]FIG. 81 is a block diagram of the digital video signal coding unitin embodiment 20.

[0192]FIG. 82 is a block diagram of the digital video signal decodingunit in embodiment 20.

[0193]FIGS. 83A and 83B are views illustrating a concept of theprocessing with the digital video signal record and playback device inembodiment 20.

[0194]FIG. 84 is a block diagram of the digital video signal decodingunit when the division by the frequency or the division by thequantization in embodiment 21 is performed.

[0195]FIG. 85 is a block diagram of the digital video signal decodingunit when the division by the bit length or the division by thequantization in embodiment 21 is performed.

[0196]FIG. 86 is a block diagram of a digital video signal decoding unitwhen the division by the resolution or the division by the quantizationin embodiment 21 is performed.

[0197]FIG. 87 is a block diagram of the digital video signal decodingunit when the division by the frequency or the division by thequantization in embodiment 22 is performed.

[0198]FIG. 88 is a block diagram of the digital video signal decodingunit when the division by the bit length or the division by thequantization in embodiment 22 is performed.

[0199]FIGS. 89A and 89B are views showing the concept of processing atthe time of skip search in embodiment 22.

[0200]FIGS. 90A and 90B are views showing a concept of processing at thetime of the inverse playback in embodiment 22.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0201] The present invention will de explained in detail on the basis ofthe drawings showing embodiments.

[0202] Embodiment 1

[0203] Embodiment 1 of the present invention will be explained. FIG. 15is a block circuit diagram showing a recording system of a digital videosignal record and playback device in embodiment 1. Referring to FIG. 15,a digital video signal outputted from an input terminal 1 is inputted toa formatting circuit 3. The video signal which is outputted from theformatting circuit 3 is inputted to a first input of a subtracter 4 anda second input of a motion compensation predicting circuit 11. An outputof the subtracter 4 is inputted to a quantizer 6 via a DCT circuit 5. Anoutput of the quantizer 6 is inputted to a first input of a buffermemory 12 via a variable-length encoder 7. In the meantime, the outputof the quantizer 6 is also inputted to an inverse DCT circuit 9 via aninverse quantizer 8. An output of the inverse DCT circuit 9 is given toa first input of an adder 10.

[0204] An output of the adder 10 is given to a first input of the motioncompensation predicting circuit 11. A first output of the motioncompensation predicting circuit 11 is given to a second input of theadder 10 and a second input of the subtracter 4. Further, a secondoutput of the motion compensation predicting circuit 11 is given to asecond input of the buffer memory 12. An output of the buffer memory 12is inputted to a modulator 14 via a format encoder 13. An output of themodulator 14 is recorded on a recording medium such as an optical discor the like via an output terminal 2.

[0205]FIG. 16 is a block circuit diagram showing a playback system inthe digital video signal record and playback device according toembodiment 1. Referring to FIG. 16, video information read from therecording medium is inputted from an input terminal 20 to a demodulator21. An output from the demodulator 21 is inputted to the format decoder23 via a buffer memory 22. The first output of a format decoder 23 isinputted to a variable-length decoder 24, and inversely quantized at aninverse quantizer 25. Then the output is subjected to the inverse DCT atan inverse DCT circuit 26 to be given to the first input of an adder 28.In the meantime, the second output of the format decoder 23 is inputtedto a prediction data decoding circuit 27. Then, the output from theprediction data decoding circuit 27 is given to the second input of theadder 28. The output of the adder 28 is outputted from an outputterminal 30 via an unformatting circuit 29.

[0206] Next, an operation of the device will be explained. The digitalvideo signal is inputted from the input terminal 1 in the unit of line,and is supplied to the formatting circuit 3. Here, in the motioncompensation prediction, one GOP is set to 15 frames as shown in FIG. 6like the conventional example to perform prediction coding with oneframe of I picture, 4 frames of P pictures (P1 through P4), and tenframes of B pictures (B1 through B10). In this case, in the formattingcircuit 3, the video data inputted in a consecutive manner is rearrangedand outputted in the unit of frame in the order shown in FIG. 7.

[0207] Further, the data inputted in the unit of line is rearranged inthe unit of block of 8×8 pixels so that macroblocks (six blocks intotal, such as adjacent four luminance signal Y blocks and two colordifference signals Cr and Cb blocks which correspond in position to theY block) is constituted. The data is outputted in the unit ofmacroblock. Here, the macroblocks are determined in the minimum unit ofthe motion compensation prediction while the motion vector for themotion compensation prediction is determined in the unit of macroblock.

[0208] Further, with the formatting circuit 3, with respect to the Ipicture, one frame of video data is divided into three areas so thatblocking is performed in this area in the unit of 8×8 pixels and themacroblock is constituted and outputted. Here, the three divided areasare set as areas 1, 2 and 3 from the top of the screen as shown in FIG.18. In FIG. 18, the area 2 located at the central part of the screen hasa size of 720 pixels×288 lines while the areas on both ends of thescreen have a size of 720 pixels×96 lines. In the meantime, in the Ppicture and the B picture, the blocking is performed without beingdivided into each area and is outputted in the unit of macroblock.

[0209] An output of the formatting circuit 3 is inputted to thesubtracter 4 and the motion compensation predicting circuit 11. Theoperation of the subtracter 4, the DCT circuit 5, the quantizer 6, thevariable-length encoder 7, the inverse quantizer 8, the inverse DCTcircuit 9, the adder 10 and the motion compensation predicting circuit11 is the same as the conventional embodiments, and the explanationthereof is omitted.

[0210] The video data outputted from the variable length encoder 7 andthe motion vector outputted from the motion compensation predictingcircuit 11 are inputted to the buffer memory 12. In the buffer memory12, the video data and the motion vector for one GOP portion arerecorded and the data is subsequently outputted in sequence to theformat encoder 13. The output of the format encoder 13 is inputted tothe modulator 14 and an error correction codes or the like are added andrecorded on the recording medium such as an optical disc or the like.

[0211] In the format encoder 13, the video data for the one GOP portionis rearranged in the data arrangement as shown in FIG. 19 and isoutputted to the modulator 14. Here, the I picture is divided into threeareas as shown in FIG. 18. When the data of the I picture correspondingto these areas 1 through 3 are set to I(1), I(2) and I(3), the data ofthe I picture is constituted so that the data is recorded in the orderof I(2), I(1) and I(3) at the front part of the data string of one GOPportion.

[0212] Further, the address where th data of each picture area is storedat the front of the GOP is recorded as header information. The number ofbytes which is occupied in the data format shown in FIG. 19 by the datain each area divided into three parts is recorded as header information.Consequently, depending on the number of bytes occupied by each areawhich is recorded in the header information, the end position of eacharea can be recognized as a relative address from the front of the GOPat the time of playback. Consequently, the optical head jumps to thefront address of the GOP in the unit of the definite time at the time ofthe special playback so that data can be read in each area in accordancewith the header information from the front of the GOP.

[0213] With a general video signal record and playback device, on thedata format at the time of data recording, the I picture is recorded inthe unit of frame. In contrast, in FIG. 19, a priority is given to anarea located at the central part of the screen out of the I picture datawhich is divided into three parts so that the area is located at thefront of one GOP. Consequently, in the case where only a part of thearea of the I picture can be decoded in a definite time at the time of ahigh speed playback, at least the playback picture at the central partof the screen can be outputted.

[0214] Subsequently, an operation at the time of playback will beexplained in accordance with FIG. 16. The demodulator 21 performs anerror correction processing so that the video signal recorded in aformat shown in FIG. 19 in the buffer memory 22 is divided into themotion vector and the video data at the format decoder 23 to beoutputted to the predicting data decoding circuit 27 and thevariable-length decoder 24, respectively. Here, an operation at the timeof the normal playback is the same as the conventional embodiment, andan explanation thereof is omitted.

[0215] At the time of a high speed playback, with respect to the datarecorded in one GOP unit on the recording medium such as an optical discor the like, the optical head jumps to the front of the one GOP in theunit of definite time so that the data part of the I picture is read inthe unit of area in accordance with the header information recorded atthe front so that the data is demodulated at the demodulator 21 and isinput to the buffer memory 22. Here, in the case where data is read fromthe recording medium such as an optical disc or the like at the time ofa high speed playback, waiting time for the disc rotation arises at thetime of jumping to the front of the GOP even when the front address ofthe GOP which is recorded on the disc is known. Consequently, when thehigh speed playback speed is increased, the time for reading the data onthe disc becomes short. Since the waiting time for the disc rotationvaries, it becomes impossible to read all the I picture data in a stablemanner.

[0216] Consequently, when the high speed playback speed is increased,after only the data of the area 2 located at the central part of thescreen is read the optical head jumps to the front of the subsequent GOPso that only the data in the area 2 that can be read is inputted to thebuffer memory 22. In this case, the format decoder 23 decodes only thearea 2 of the I picture that can be read. On the other hand, the areas 1and 3 whose data are not read are masked by the gray data, and a highspeed playback picture is outputted. Consequently, in the case where oneGOP is set to 15 frames, a 15 times speed special playback picture canbe obtained.

[0217]FIG. 20 shows a playback picture in the case where a high speedplayback is performed by playing back only the area 2 of the I picturefrom the nth GOP of one GOP up to the n+3th GOP. In FIG. 20, the areas 1and 3 on both ends of the screen in FIG. 20 are masked by the gray data.Further, when the information amount of the I picture is small and thedisc rotation wait time is short, and time is available for reading datain the areas 1 and 3, the data of the areas 1 and 3 is not decoded. Thisis because all the data of one screen portion cannot be read in a stableway at the time of a high speed playback, and if a screen is outputtedonly when the data in the areas 1 and 3 can be read, these areas cannotbe outputted in a definite interval so that a high speed playbackpicture becomes unnatural.

[0218] As described above, since the I picture used for the specialplayback as shown in FIG. 19 is arranged so that a priority is given tothe area located in the center of one screen is recorded on therecording medium at the front of G82 one GOP, only the data of the area2 located at the center is read for a high speed play back even when thehigh speed playback speed is increased with the result that the contentof the playback picture is easy to see. Further, since only the data inthe region of the area 2 is read from the recording medium, a higherspeed special playback can be realized compared with a case in which thewhole I picture is read.

[0219] In, the aforementioned embodiment 1, the I picture is dividedinto three areas in the vertical direction as shown in FIG. 18 and isrecorded, the picture is not necessarily divided into three areas. Thearea may be divided into n areas (n>1) in the unit of slice defined inthe international standard MPEG for recording the data. Here, the slicehas a one dimension structure of macroblocks of a arbitrary number oflengths (one or more) so that when the right end of the screen isattained, the display continues to the left end one line below.

[0220] Embodiment 2

[0221] Next, embodiment 2 of the present invention will be explainedwith respect to drawings. FIG. 21 is a conceptual view for explaining amethod for special playback in the case where data extension inembodiment 2 is performed. In embodiment 1, the I picture is dividedinto three areas as shown in FIG. 18 so that only the data of the area 2located at the center of the area is read and played back. Thus, withrespect to the areas 1 and 3, the mask data is outputted. However, thedata of the area 2 is extended to a size of one screen as shown in FIG.21.

[0222] In this case, at the time of converting the video signal intodata in the unit of line with the unformatting circuit 29, the data ofthe area 2 is interpolated to be extended to a size of one screenportion and is outputted. In the case of FIG. 21, the area 2 has a sizeof 720 pixels×288 lines and is constituted in 144 line symmetric invertical directions from the center of the screen.

[0223] Here, at the time of the special playback, when the upper halfpart of the area 2 is set to AR2 a and the lower half part is set to AR2b as shown in FIG. 21A, AR2 a and AR2 b are extended by 1.5 times in thevertical direction respectively to synthesize playback pictures AR2 a′and AR2 b′ as shown in FIG. 21B. With respect to the method forextending the pictures, when the data in the unit of each line of AR2 ais defined as AT(l)(l: line number 1≦l≦144), and line data in the upperhalf part of the extended screen is set to DT(m) (1≦m≦240), extension ismade which is represented by the following expressions.

DT(3n−2)=AT(2n−1)

DT(3n−1)=AT(2n−1)

DT(3n)=AT(2n)(n=1 to 80)

[0224] In the meantime, when the data in the unit of each line of AR2 bis defined as AB(l) (l: line number 1≦l≦144), and line data in the lowerhalf part of the extended screen is set to DB(m) (1≦m≦240), extension ismade which is represented by the following expressions.

DB(3n−2)=AB(2n−1)

DB(3n−1)=AB(2n−1)

DB(3n)=AB(2n) (n=1 to 80)

[0225] As described above, only the data of the area 2 located at thecenter of screen at the time of the high speed playback is read and isextended to a size of one screen portion and is outputted as a playbackpicture. Consequently, since both ends of the playback picture at thetime of a high speed playback is not masked, the playback picture ceaseto be favorable to watch.

[0226] In the aforementioned embodiment 2, the screen is extended in thevertical direction by inserting data simply in the unit of line. Theline data may be linearly interpolated with respect to the verticaldirection.

[0227] Embodiment 3

[0228] Embodiment 3 of the present invention will be explained. Astructure of a recording system and a playback system of the digitalvideo signal record and playback device in embodiment 3 is the same asembodiment 1 (see FIGS. 15 and 16).

[0229] Next, an operation of the device will be explained. A digitalvideo signal is inputted in the unit of line from the input terminal 1and is supplied to the formatting circuit 2. Here, in the motioncompensation prediction, one GOP is set to 15 frames like theconventional example as shown in FIG. 6. Then, the GOP is subjected tothe prediction coding as one frame of I picture, four frames of Ppictures (P1 through P4), 10 frames of B pictures (B1 through B10). Inthis case, in the formatting circuit 3, the video data inputted in acontinuous manner like the conventional example is rearranged in theunit of frame in an order as shown in FIG. 7 and is outputted. Further,the data inputted in the unit of line is rearranged in the unit of blockhaving 8×8 pixels to constitute a macroblock (a total of six blocks ofadjacent four luminance signal Y blocks and two color difference signalsCr and Cb blocks) shown in FIG. 17 so that the data is outputted in theunit of macroblock. Here, the macroblock is the minimum unit of themotion compensation prediction, and the motion vector for the motioncompensation prediction is determined in the unit of macroblock.

[0230] Further, in the formatting circuit 3, the I picture is dividedinto five areas for each of 720 pixels×96 lines in the verticaldirection of one frame of video data. In this area, 8×8 pixels areblocked to constitute a macroblock for the output. In this case, dividedfive areas are defined as areas 1, 2, 3, 4 and 5. In the meantime, the Ppicture and the B picture are blocked without being divided into areasand is outputted in the unit of macroblock.

[0231] The output of the formatting circuit 3 is inputted to thesubtracter 4 and the motion compensation predicting circuit 11, but theoperation of the subtracter 4, the DCT circuit 5, the quantizer 6, thevariable length encoder 7 and the inverse quantizer 8, the inverse DCTcircuit, the adder 10, and the motion compensation predicting circuit 11is the same as the conventional embodiment and an explanation thereof isomitted. outputted to the format encoder 13 in sequence. The output ofthe format coder 13 is inputted to a modulation circuit 14 so that anerror correction code or the like is added and is recorded on therecording medium such as an optical disc or the like.

[0232] In the format encoder 13, the data of the GOP portion isoutputted to the modulator 14 by rearranging the video signal in thedata arrangement as shown in FIG. 23. The I picture are divided intofive areas as shown in FIG. 22 so that the data of the I picturecorresponding to areas 1 through 5 are defined as I(1), I(2), I(3), I(4)and I(5). In FIG. 23, the data of the I picture is constituted to berecorded in the order of I(1), I(2), I(3), I(4) and I(5) at the front ofa data stream for one GOP so that priority is given to the area whichcomes to the center of the screen.

[0233] Further, in FIG. 23, the address where the data of each Ipictures is stored is written as header information. As the headerinformation, the number of bytes which the data in each area occupies onthe data format is recorded, the area being obtained by dividing the Ipicture into five parts. Consequently, at the time of the playback, itis possible to recognize the end position of each area as a relativeaddress with respect to the front of the GOP on the basis of the numberof bytes occupied by each area which is recorded in header informationat the time of the playback. As a consequence, the optical head jumps tothe front address of the GOP in the unit of a definite time so that thedata of the I picture can be read in the unit of area in accordance withthe header information from the front of the GOP.

[0234] With a general video signal record and playback device in commonuse, in the data format at the time of recording, the I picture isrecorded in the unit of frame. In contrast, in FIG. 23, a priority isgiven to an area located at the central part of the screen out of thefive areas obtained by dividing the I picture to be arranged at thefront of one GOP with the result that the playback picture at least atthe central part of the screen can be outputted even in the case whereonly the area in part of the I picture can be decoded.

[0235] Subsequently, an operation at the time of playback will beexplained in accordance with FIG. 16. A video signal which is subjectedto an error correction processing in the demodulator 21 and is recordedin a format of FIG. 23 in the buffer memory 22 is divided into themotion vector and the video data which are outputted to the predictiondata decoding circuit 27 and the variable-length decoder 24,respectively. Here, the operation at the time of the normal playback, isthe same as the conventional embodiments, a detailed explanation thereofis omitted.

[0236] At the time of a high speed playback, with respect to the datarecorded on the recording medium such as an optical disc or the like,the optical head jumps to the front of the GOP in the unit of a definitetime to read the data part of the I picture in accordance with theheader information and the data is demodulated at the demodulator 21 tobe inputted to the buffer memory 22. However, in the case where theinformation amount of the I picture is too large to be read in adefinite time, the data which has been half read is read to the lastitem of the data, and the optical head jumps to the front of thesubsequent GOP to input only the data that can be read into the buffermemory 22. In such a case, in the format decoder 23, only the area ofthe I picture that can be read is decoded and is outputted as a highspeed playback picture. Consequently, when one GOP is set to 15 frames,a 15 times speed special playback picture can be obtained.

[0237]FIG. 24 shows a playback picture in the case where only the Ipicture of one GOP is played back. In this case, the information amountof all areas of the I pictures is too large to be read from therecording medium, with respect to the area which cannot be read, data ofthe preceding area is held as they are to be outputted therebysynthesizing the high speed playback picture. In FIG. 24, in the casewhere the n+1th GOP area 5 and n+3th GOP areas 1 and 5 cannot be read,the playback picture immediately before the playback picture is held asit is.

[0238] In this manner, the I picture used in the special playback asshown in FIG. 23 is positioned so that the priority is given to the arealocated at central part of the screen just above the screen to berecorded on the recording medium at the front of one GOP. Thus even whenthe whole I pictures cannot be read, the central part of the screen isgiven a priority in playback so that the content of the playback pictureis easy to understand.

[0239] In the aforementioned embodiment 3, when the whole I picturescannot be read, the playback picture is interpolated in the unit ofarea, the interpolation may not be made in the unit of area, but may bemade in the unit of error correction block.

[0240] In this case, the demodulator 21 segments data into severalbyte-long packets with respect to the data arrangement shown in FIG. 23,and a error correction code is added to each packet. FIG. 25 shows anexample of a case in which data in five areas inputted in a consecutivemanner is divided into packets in the unit of error correction blockunit. FIG. 25A shows a data string before the packet division. FIG. 25Bshows data after the packet division. Five areas of the I picture aredivided into packets with a definite volume and the area I(3) is dividedinto packets from 1 through i and the I(4) is divided into packets ithrough j for the input.

[0241] At the time of a high speed playback, the optical head jumps tothe front of the GOP in the unit of a definite time with respect to datarecorded on the recording medium such as an optical disc or the like inthe unit of GOP to read the data portion of the I picture in the unit ofarea in accordance with the header information. The data portion isdemodulated by the demodulator 21 to be inputted to the buffer memory22. However, in the case where the whole I picture cannot be read in adefinite time because the information amount of the I picture is large,the optical head jumps to the front of the subsequent GOP even when theone area portion of data is being read. Further, data which can be readis subjected to the error correction processing so that the data whichcan be error corrected is inputted to the buffer memory 22. In thiscase, the format decoder 23 recognizes an address of the I picture areawhich can be decoded to the midway so that the data which can be read isdecoded in the unit of macroblock and is outputted as a high speedplayback picture. In this case, with respect to the macroblock whichcannot be decoded, data of the preceding screen is held and outputted atit is.

[0242] In the aforementioned embodiment 3, data in each area of the Ipicture is divided into packets in a consecutive manner. However, datamay be divided so that the data in two or more areas may not be includedin one packet. In this case, data in one area portion is closed ininteger times of the error correction block with the result that thedata can be rearranged in the unit of area immediately after the errorcorrection processing. When data in each area is divided into the unitof packet, data is inputted halfway to the last packet of each area sothat the residual data is required to be placed in data masking (forexample, all the data is masked to “1”).

[0243] In addition, in the aforementioned embodiment 3, a priority isgiven in the order of 3, 2, 4, 1 and 5. However, the order is notlimited to this order. The order may be, for example, 3, 4, 2, 5 and 1.

[0244] In addition, in the aforementioned embodiment 3, the I picture isdivided into five areas in the horizontal direction and recorded asshown in FIG. 22. The data is not required to be divided into fiveareas, but the data may be divided into n areas (n>1) in the unit ofslice defined by the international standard MPEG. Here, the slice has aone dimensional structure of macro blocks with an arbitrary number oflengths (one or more). The slice is a belt which continues to the leftend one line below upon reaching the right end of the screen.

[0245] Embodiment 4

[0246] Next, embodiment 4 of the present invention will be explainedwith respect to drawings. FIG. 26 is a view showing a special playbackmethod in embodiment 4. In embodiment 3, a special playback is performedwith a playback method shown in FIG. 24. However, the special playbackmay be performed so that the playback picture as shown in FIG. 26 isoutputted. In this case, the format decoder 23 synthesizes one screen byplaying back each one area from the I pictures of five GOP's which arecontinuous as shown in FIG. 26. For example, in FIG. 26A, one screenportion of the playback picture is synthesized from the I pictures ofnth to the n+4th GOP so that the I picture of the n+4th GOP is playedback in area 1, the I picture of the n+3th GOP is played back in area 2,the I picture of the n+2th GOP is played back in area 3, the I pictureof the n+1th GOP is played back in area 4, and the I picture of the nthGOP is played back in area 5. Further, referring to FIG. 26, when anattention is paid to the area 5, the I picture of the nth, n+1th,n+2th - - - GOP are played back as the played back video data.

[0247] Further, when the whole I picture cannot be read during adefinite time because the information amount of the I picture is large,the data preceding by one screen is held as it is and is outputted tosynthesize a higher speed playback picture. FIG. 27 is a playbackpicture when the n+1th GOP area 5, and n+3th GOP areas 1 and 5 cannot beread. In this case, since the data arrangement is recorded on therecording medium by giving a priority to the an area located at thecentral part of the screen as shown in FIG. 23, the central portion ofthe screen is given a priority in the playback even in the case wherethe whole I picture cannot be read in terms of time with the result thatit never happens that the playback picture is hard to see. Further, evenin the case where data in two or more areas cannot be read, one screenis divided into five areas. Since the frame played back in each area isdifferent, it is hard to detect that data is lacking in the playbackpicture.

[0248] Embodiment 5

[0249] Next, embodiment 5 of the present invention will be explainedwith respect to the drawings. FIG. 28 is a view showing an arrangementstructure of a digital video signal data according to embodiment 5. Inembodiment 3, the data arrangement is written in the order of the areas3, 2, 4, 1 and 5 with respect to the I picture as shown in FIG. 23. Thearrangement may have a structure shown in FIG. 28. In FIG. 28, when thedata of the I picture is recorded at the front portion of the dataarrangement of one GOP portion, the area number at the front of each ofthe GOPs is scrolled. In other words, as shown in FIG. 28, when the Ipicture data is recorded in the order of I(5), (1), I(2), I(3) and I(4)in the nth GOP, the I picture data is recorded in the order of I(1),I(2), I(3), I(4) and I(5) in the n+1th GOP. Further, I(2) comes first inthe n+2th GOP. When the GOP number becomes n+3 and n+4 and - - - , thefront area is sequentially scrolled and recorded in the order of I(3),I(4), I(5), I(1) and - - - .

[0250] Further, at the front of the GOP, the address where data in eachI picture is stored and information for recognizing the kind of thefront area are written as header information. As header information, thearea number recorded at the front and the number of bytes indicatingdata amount occupied on the data format of each area as shown in FIG.27. Consequently, at the time of the playback, the data order of the Ipicture area and the end position of the each area on the recordingmedium can be recognized as relative addresses with respect to the frontof the GOP, with the front area number recorded in the headerinformation and the number of bytes occupied by each area on therecording medium. Consequently, at the time of the special playback, theoptical head jumps to the front address of the GOP in the unit of acertain period of time, so that the I picture data can be read for eacharea from the front of the GOP in accordance with the headerinformation.

[0251] In this case, the position where the I picture area divided intofive areas is recorded is scrolled in the unit of GOP so that the areawhich cannot be decoded is not concentrated on the fixed position on thescreen even when only part of the area of the I picture can be decodedat the time of the special playback.

[0252] At the time of the high speed playback, the optical head jumps tothe front of the GOP in the unit of certain time with respect to thedata recorded on the recording medium such as an optical disc or thelike to read the data portion of the I picture in the unit of area inaccordance with the header information and is demodulated at thedemodulator 21 and is inputted to the buffer memory 22. However, whenthe information amount of the I picture is too large to read the whole Ipicture in a certain time, the optical head jumps to the front of thesubsequent GOP after reading to the last data in the area which is readhalfways to input only the data in the area that can be read into thebuffer memory 22. In this case, the format decoder 23 decodes only thearea of the I picture that can be read, which is outputted as a highspeed playback picture. Consequently, in the case where one GOP is setto 15 frames, a 15 times speed special playback picture is obtained.

[0253]FIG. 29 shows a playback picture in the case where the I pictureof one GOP is played back in a high speed playback. In this case, the Ipicture is to be recorded on the recording medium in an order as shownin FIG. 28. Here in the case where the information amount of the Ipicture is large, and the whole I picture cannot be read in time, thedata of the preceding screen is held as it is and is outputted so that ahigh speed playback picture is synthesized. FIG. 29 shows a case inwhich n+1th GOP area 5 and n+3th GOP areas 1 and 2 cannot be readcompletely. In this case, the data of the preceding screen is held as itis.

[0254] As described above, the order of recording the I picture used forthe special playback as shown in FIG. 28 is scrolled in the unit of GOP.Consequently, even in the case where only some areas of the I picturecan be decoded at the time of the special playback, the area that cannot be decoded is not concentrated on the fixed position on the screen.

[0255] Embodiment 6

[0256] Next, embodiment 6 of the present invention will be explainedwith respect to drawings. FIG. 30 is a view showing a data arrangementstructure of a digital video data according to embodiment 6. In thiscase, the I picture and the P picture are divided into five areas eachhaving 720 pixels×96 lines so that each area is blocked in the unit ofthe macroblock and is coded as shown in FIG. 22. However, the P pictureis divided into five area. The motion compensation prediction isperformed and coded in such a manner that the retrieval scope of thereference pattern of the motion compensation prediction closes in thearea. Here, the divided five areas are defined as areas 1, 2, 3, 4 and 5from the top. Further, with respect to the B picture, the motioncompensation prediction is performed and coded without being dividedinto areas.

[0257] With the format encoder 13, the data of one GOP portion is usedto rearrange the video signal with the data arrangement shown in FIG. 30and is outputted to the modulator 14. Here, with respect to the Ipicture and the P picture, one screen is divided into five areas asshown in FIGS. 22. The I picture, and the P1, P2, P3 and P4 pictures aredefined as I(1) through I(5) and Pi(1) through Pi(5) (i=1 through 4). InFIG. 30, the data of the I picture, the P1, P2, P3 and P4 pictures isconstituted to be recorded in the order of 3, 2, 4, 1 and 5 from thefront of the data string for one GOP portion, so that the area locatedat the central part of the screen is given a priority. Further, in FIG.30, the data amount of each area is recorded as header information atthe front of one GOP so that the address of the data in each I pictureand P picture area can be recognized.

[0258] At the time of the high speed playback, the optical head jumps tothe front of the GOP with respect to the data which is recorded in theunit of one GOP on the recording medium such as optical disc or the likewith the result that the data portion of the of the I picture and the Ppicture is read in the unit of area and is demodulated by thedemodulator 21 and is inputted to the buffer memory 22. However, whenthe information amount of the I picture and the P picture is too largeto read the whole I pictures and P pictures in a definite time, theareas read halfways are read to the last. Then the optical head jumps tothe front of the GOP in the unit of a certain time so that only the datathat can be read is inputted to the buffer memory 22. In this case, theformat decoder 23 decodes only the areas of the I picture and the Ppicture that can be read and then output the data as a high speedplayback picture. Consequently, in the case where the one GOP is set to15 frames, a triple speed special playback picture can be obtained.

[0259] Further, since the area located at the central part of the screenis given a priority to be arranged at the front of one GOP out of the Ipicture divided into five sections, at least a playback picture at thecentral part of the screen can be outputted even in the case where onlya part of either the I picture or the P picture can be decoded. Furtherthe pictures are recorded on the recording medium in the order of the Ipicture, the P1 picture, the P2 picture, the P3 picture and the P4picture. Consequently, it never happens that the reference data cannotbe played back at the prediction data decoding circuit 27 even when allthe data cannot be read.

[0260]FIG. 31 shows a play back picture in the case where a high speedplayback of the picture is performed by playing back only the I pictureand the P picture in one GOP. In this case, when the whole I picture andthe whole P pictures cannot be read from the recording medium in adefinite time because the information amount of the I picture and the Ppictures are large, the data of the preceding screen is held as it isand outputted to synthesize a high speed playback picture with respectto the area that cannot be read. FIG. 31 shows the case where the areas3, 4 and 5 of the P4 of the nth GOP cannot be read. In this case, thedata of the preceding screen is held as it is.

[0261] As described above, as shown in FIG. 30, the I picture and the Ppictures are played back to output a special playback picture at thetime of the special playback by collecting and arranging the I pictureand the P picture used at the time of special playback in the unit ofarea at the front of the one GOP. Further, in the case where the whole Ipicture and the whole P picture cannot be read because of time limit,the data of the preceding screen is interpolated to allow output of theplayback picture.

[0262] In the aforementioned embodiment 6, in the case where the whole Ipicture and the whole P picture cannot be read, the playback picture isinterpolated in the unit of area. However, the interpolation may not beperformed in the area unit, but it may be performed in the unit of errorcorrection code.

[0263] In this case, the demodulator 21 segments the data into packetsof several bytes with respect to the data arrangement shown in FIG. 30so that an error correction code is added to each of the packets. FIG.32 shows a case in which the data of five areas inputted to FIG. 32 in acontinuous manner is divided into packets of error correction blocks.FIG. 32A shows the data string before the packet division. FIG. 32Bshows the data after the packet division. In FIG. 32, the data isdivided into ith through jth packets in the area P1(3).

[0264] At the time of the high speed playback, the optical head jumps tothe front of the GOP in the unit of a definite time with respect to thedata which is recorded in the unit of GOP on the recording medium suchas an optical disc or the like with the result that the data portion ofthe I picture is read in the unit of area in accordance with the headerinformation and is demodulated at the demodulator 21 and is inputted tothe buffer memory 22. However, in the case where the information amountof the I picture is so large that the whole I picture and the whole Ppictures cannot be read in a definite time, the optical head jumps tothe front of the next GOP even in the midst of reading the data in onearea portion. Further, the data that has been read is subjected to anerror correction processing, and the data that can be error corrected isinputted to the buffer memory 22. In this case, the format decoder 23recognizes the address of the I picture and the P pictures that can bedecoded halfways so that the data that can be read is decoded in theunit of macroblock and is outputted as a high speed playback picture. Inthis case, with respect to the macroblock that cannot be decoded, thedata of the preceding screen is held at it is and is outputted.

[0265] In the aforementioned embodiment 6, in the motion compensationprediction, the scope of retrieval is set to be closed in each area, butit is not always required to be closed.

[0266] Embodiment 7

[0267] Next, embodiment 7 of the present invention will be explainedwith respect to FIG. 33. FIG. 33 is a view showing a method for aspecial playback according to embodiment 7. In embodiment 6, the specialplayback is performed in a playback method as shown in FIG. 31. However,the special playback may be performed so that the playback picture isoutputted as shown in FIG. 33. In this case, the format encoder 23synthesizes one screen by playing back areas one by one from continuousfive frames as shown in FIG. 33. In FIG. 33A, a playback picture of onescreen portion is synthesized from the I picture, the P1 through P4pictures. Further, in FIG. 33A, the P4 picture is played back in thearea 1, the P3 picture is played back in the area 2, the P2 picture isplayed back in the area 3, and the P1 picture is played back in the area4 and the I picture in the area 5. Further, in FIG. 33, the area 5 isnoted with the passage of time. The played back video data includes theI picture of the nth GOP, the P1, P2, P3 and P4, and the I picture ofthe n+1th GOP picture, and the P1 picture.

[0268] Further, in the case where the information amount of the Ipicture and the P picture is so large that all the I picture and the Ppicture cannot be read in a definite time, the data of the precedingscreen is held as it is and is outputted to synthesize a high speedplayback picture. FIG. 34 shows a playback picture in the case where theareas 1, 4 and 5 of the n-th GOP cannot be read. In this case, as shownin FIG. 30, with respect to the data string, the area located at thecenter on the screen is given the priority to be recorded on therecording medium with the result that it never happens that the playbackpicture is hard to see because the central part of the screen in giventhe priority in the playback. Further, even in the case where the datain two or more areas can not be read, one screen is divided into fiveareas and the frame played back in each area is different, it is hard tosee that the data is lacking in the playback picture.

[0269] Embodiment 8

[0270] Next, embodiment 8 of the present invention will be explainedwith respect to drawings. FIG. 35 is a view showing a digital video dataarrangement structure in embodiment 8. In embodiment 6, the dataarrangement is written in the order of the areas 3, 2, 4, 1 and 5 asshown in FIG. 30, but the arrangement may have a structure as shown inFIG. 35.

[0271] In FIG. 35, when the data in the I picture and the P pictures arerecorded at the front of the data arrangement for one GOP portion, thearea number at the front is scrolled for each of the frames. In otherwords, as shown in FIG. 28, in the nth GOP, the I picture data isrecorded in the order of the P1(2), P1(3), P1(4), P1(5) and P1(1).Further, in the P2 picture, P2(3) comes to the front. In the P3 picture,and the P4 picture, the front areas are scrolled and recordedsequentially like P3(4) and P4(5).

[0272] Further, at the front of the GOP, the address where the data ofthe I picture and the P picture are stored, and information foridentifying the kind of the area at the front of each frame are recordedas header information. Here, as header information, the area numberwhich is recorded at the front of each area and the number of bytesindicating the data amount in each area which is divided into five partsare recorded. Consequently, the optical device jumps to the front of theGOP in the unit of a certain time at the time of the special playback sothat the data can be read in the unit of area in accordance with theheader information.

[0273] In this case, since the position where the I picture and Ppicture areas divided into five parts are scrolled in the unit of frame,it never happens that the area which is not decoded is not concentratedon the fixed position on the screen even in the case where only a partof the areas of the I picture and the P picture can be decoded.

[0274] At the time of the high speed special playback, the data which isrecorded on the recording medium such as an optical disc or the like inthe unit of one GOP is read in the unit of area unit in accordance withheader information. Then, the data is demodulated by the demodulator 21and is inputted to the buffer memory 22. However, when the informationamount of the I picture and the P picture is so large that the whole Ipicture and the whole P picture cannot be read in a definite time, thedata is read to the last with respect to the area read halfways. Then,the optical head jumps to the front of the GOP to input data only of thearea which can be inputted into the buffer memory 22. In this case, theformat encoder 23 decodes only the area of the I picture and the Ppicture, and is outputted as a high speed playback picture.

[0275]FIG. 36 shows a playback picture in the case where only the Ipicture and the P picture in one GOP are played back for a high speedplayback. In this case, when the data amount of the I picture and the Ppicture is so large that the whole I picture and P picture cannot beread in a definite time, a high seed playback picture is synthesized byholding and outputting the data of the preceding screen as it is. FIG.36 shows a case where the areas 3, 4 and 5 of the P4 of the nth GOPcannot be read. In this case, the data of the preceding screen is heldas it is.

[0276] As described above, since the order of recording the I pictureused for the special playback is scrolled in the unit of GOP a shown inFIG. 35, the area which cannot be decoded is not concentrated on thefixed position on the screen even in the case where only a part of theareas of the I picture can be decoded at the time of the specialplayback.

[0277] Embodiment 9

[0278] Next, embodiment 9 of the present invention will be explainedwith respect to FIG. 37. FIG. 37 is a block diagram on the recordingside showing a digital video signal coding processing unit in a digitalvideo record and playback device wherein the DCT block is divided intostages in the low frequency area and the high frequency area so thatonly the low frequency area is located at the front of the GOP. In FIG.37, reference numeral 51 denotes a buffer memory, 52 a subtracter, 53 aDCT circuit, 54 a quantizer, 55 a variable-length encoder, 56 an inversequantizer, 57 an inverse DCT circuit, 58 an adder, 59 a motioncompensation predicting circuit, 60 a counter for counting the number ofevents and a code amount, 61 a format encoder, and 65 an input terminal.

[0279] Next, an operation of the device will be explained. The videodata to be inputted is an interlace picture which has an effectivescreen size of horizontal 704 pixels and vertical 480 pixels. Here, theoperation of the subtracter 52, the DCT circuit 53, the quantizer 54,the variable-length encoder 55, the inverse quantizer 56, the inverseDCT circuit 57, the adder 58 and the motion compensation predictingcircuit 59 are the same as the counterparts shown in conventionalembodiments. Thus, an explanation thereof will be omitted.

[0280] An operation of the variable-length encoder 55 will be explainedwith respect to FIG. 38. FIG. 38 shows a data arrangement of DCTcoefficients inside of a DCT block. In FIG. 38, a low frequencycomponent is located at the upper left portion and the data of the DCTcoefficient of a high frequency component is located at the lower rightportion. The data of the low frequency coefficient up to a specificposition (the end of the events) (for example, the hatching part in FIG.38) out of the data of the DCT coefficient arranged in the DCT block iscoded into a variable-length code as a variable-length area and isoutputted to the format encoder 61. Then, the variable-length coding isapplied to the data of the DCT coefficient after the data of the DCTcoefficient at the aforementioned position. In other words, the data inthe space frequency area is coded through partitioning.

[0281] A boundary between the low frequency area and the high frequencyarea is referred to as a breaking point. The breaking point is set toassume a predetermined code amount in the low-frequency area which theoptical head can assess at the time of the special playback. Thevariable-length encoder 55 divides the DCT coefficient into thelow-frequency area and the high-frequency area in accordance with thebreaking point to be outputted to the format encoder 61.

[0282] The determination of the coding area is performed at the boundaryof the event. It goes without saying that the determination can be madeby other methods. For example, the determination of the coding area canbe made at the boundary of the fixed number of events. The data may bedivided with the quantizer 54 with the quantization data subjected to arough quantization with the quantizer 54 and a differential valuebetween a fine quantization and a rough quantization. Further, the datamay be divided with coding of a picture whose space resolution isthinned to a half level with the buffer memory and a coding of adifferential picture between a picture whose resolution is brought backfrom the half level and a picture with an original resolution. In otherwords, the data division is not limited to the division of the frequencyarea. It goes without saying that the high efficiency coded data of thepicture may be divided by the quantization and the division of the spaceresolution.

[0283] At this time, more important data as a picture is a low frequencyarea data in the division by the frequency. When the division is thedivision by quantization, the data is subjected to a rough quantizationfor coding. When the data is divided with the space resolution, thethinned picture is coded. By decoding only these important data, adecoded picture can be obtained which can be easily perceived by man. Inthis manner, one high efficiency coded data is divided into morefundamental and important data and other data (this process is referredto as hierarchization). An error correction code is added and modulationis performed to be recorded on a disc.

[0284] In this manner, since only the low-frequency component of the Ipicture and the P picture are divided, reading and playing back onlythese low-frequency components at the time of the special playbacklargely reduces the amount of data which is read at the time of thespecial playback. As a consequence, time for reading data from themedium becomes shorter so that a high speed playback of a smoothmovement can be realized at the time of skip search. Further, when onlythe I picture and the P picture are arranged in a consecutive manner,the data of the low-frequency component of the I picture and the Ppicture can be easily read from the disc to be decoded. In this case,more efficient data structure can be made by extracting and arrangingonly the low-frequency component than by arranging the whole area of theI picture and the P picture at the front of the GOP.

[0285] Next, an operation of the format encoder 61 will be explained.FIG. 39 is a flowchart showing a movement of a format encoder. In thebeginning, when the encoding operation is started, it is judged that theencoding mode is in a hierarchical mode or not. When the mode is not thehierarchical mode, information is inserted into a system stream whichinformation is representative of the fact that the mode is anonhierarchical mode to follow the conventional stream structure. In thecase of the hierarchical mode, the setting of the sequence header isconfirmed. Specifically, the data of the sequence scalable extension isconfirmed. When the data is written correctly, the front of the pictureis recognized so that the I picture and four P pictures are separatedinto the data of the low-frequency component and the data of the higharea component to detect respective data lengths.

[0286] In the meantime, the length of the data of the B picture isdetected for each of the pictures. Further, a packet is prepared whereonly address information is recorded in the case where the data of thelow-frequency component of the I picture and the P pictures area isarranged to follow the front of the GOP. In this packet, addressinformation for the low-frequency component of the I picture and the Ppicture, the high-frequency component of the I picture of the fourpictures and ten B pictures are contained so that the data length forthe respective data is recorded.

[0287] Consequently, the front position of respective data stream isobtained as a relative address with respect to the front of the GOPheader from this data length. The packet containing this addressinformation and the low-frequency component of the I picture and four Ppictures as well as the remaining data are sequentially arranged to beformatted.

[0288] Out of them, the confirmation of the scalable mode on thescalable extension of the aforementioned sequence header refers to theconfirmation of the scalable mode setting which is determined in thesyntax of the MPEG2 of FIG. 40 and the confirmation of the descriptionof the priority break point on the slice header. The priority breakpoint is located at a predetermined number of events of FIG. 40(corresponding to the aforementioned breaking point) and refers to thedata representative of the boundary between the divided low-frequencycomponent and the high-frequency component.

[0289] When a scramble mode assumes “00” it is shown that the followingbitstream is a bitstream of a data partitioning. It is also shown thatthe bitstream which is divided into the low-frequency component and thehigh-frequency component continues. When the B picture consists of thelow-frequency component so that no high-frequency component isgenerated, the B picture is not divided.

[0290] One example of the bitstream which is generated in this manner isshown in FIG. 41. FIG. 41A shows a bitstream which is not hierarchized.When the bitstream is hierarchized with a circuit shown in FIG. 37, thebitstream is divided and hierarchized as shown in FIG. 41B. When thisdata is arranged in an array in consideration of this special playback,the low-frequency component of the I picture and the P picture isarranged at the front of the GOP as shown in FIG. 41C.

[0291]FIG. 41D shows a data arrangement in the case where addressinformation is contained in the private packet as shown in a flowchartin FIG. 39. In this case, the address information may be representedwith a relative address with respect to the front of the GOP header asdescribed above. However, the address information may be represented insuch a manner that which byte of which packet is the front of eachpicture. It goes without saying that the address information may berepresented with a sector address on the disc as well.

[0292]FIG. 42 shows an example in which address information is containedin a private packet. When a packetized elementary stream (which isreferred to as PES) packet is used as a private packet, the stream ID isspecified in BF (hexadecimal number representation). After describingthe packet length, the byte MSB is set to 1 and the subsequent bit isset to 0 so that the code does not become the same as all the startcodes (start code of packet and the start code of the bitstream). Thenthe hierarchical mode, the kind of hierarchization, the kind of pictureto be used at the time of the special playback, and the number of thestart addresses or the like are described with the remaining six bits.

[0293] After that, the 21 bit long address information is described sothat the GOP data amount can be represented up to a maximum length of 2Mbytes. However, 100 (represented in binary representation) is insertedinto the first 3 bits out of 21 bits of data so that the data does notbecome the same as the front 24 bits 000001 (hexadecimal representation)of the start code as described above. Here, the start address includes astart address of the low-frequency component of the I picture, a startaddress of the high-frequency component of four P pictures and a startaddress of the high-frequency component of the I picture, thehigh-frequency component of four P pictures, and a start address of tenB pictures. Further, a sector address on a disc where the data of thepreceding and succeeding GOP is recorded is added to jump an opticalhead at the time of the special playback.

[0294] When the 1 bit parity is added to the 21 bit addresses, thereliability of the data is heightened. In this case, 10 (binaryrepresentation) may be added to the front with respect to 21 bits +1bit. Further, in consideration of the high-speed times of the specialplayback, the variation in the high-speed times of the special playbackis widened when the sector address of the several front and rear GOPs isadded as well as the address of the preceding and succeeding GOP.Further, it is shown that address information is described in theprivate two packets of the PES packet. It goes without saying that thesector address may be written on other user areas or the like such asprivate descripter of a program stream map or the like.

[0295] The playback side of embodiment 9 will be explained with respectto FIG. 43 and FIG. 44. FIG. 43 is a block diagram of a digital videosignal decoding processing part. In FIG. 43, reference numeral 71denotes a program stream header detector, 72 a PES packet headerdetector, 73 a video bitstream generator, 74 a data rearranger, 75 anaddress memory, 76 a mode switcher, 77 a variable-length decoder, 78 aswitch, 79 an inverse quantizer, 80 an inverse DCT circuit, 81 an adder,62 a prediction data decoding circuit, 83 a frame memory and 64 adecodable determiner. FIG. 44 is a view showing an operation concept ofFIG. 43.

[0296] Next, an operation of FIG. 43 will be explained with respect toFIG. 45. FIG. 45 is a flowchart showing an operation of a format decoderat the time of the playback. The bitstream outputted from the ECC isdetected the header of a program stream to be divided into each PESpacket. Further, the PES packet header is detected to differentiate aprivate packet including address information and a video packet.

[0297] In the case of a private packet, the address informationcontained in the packet is extracted and stored. In the meantime, in thecase of the video packet, the bitstream of the video data is extracted.Here, in the case of the normal playback, the data of the low-frequencycomponent and the high-frequency component is extracted from thebitstream stream of the video data with respect to the I picture and theP picture so that the data is rearranged and a playback picture isoutputted. In the meantime, at the time of the special playback, onlythe low-frequency component of the video data is extracted and playedback. Here, after the low-frequency component is played back, theoptical head is allowed to jump to the front of the subsequent GOP.

[0298] In this case, when these addresses are described in the videostream, the address information is extracted and stored after beingconverted into the bitstream. Consequently, in the case where theaddress information is described in the private descripter of theprogram stream map, the address information is extracted and stored at alevel of the detection of the program stream header. It goes withoutsaying that the address information may be either a relative address oran absolute address.

[0299] In actuality, a mode signal of such as skip search and a normalcontinuous playback or the like is inputted to the mode switcher 76. Inthe meantime, a playback signal from a disc or the like is amplified byan amplifier so that the signal is played back with a clock which hasbeen subjected to a phase synchronization and outputted from a PLL orthe like. Next, a differentiation operation is performed for digitaldemodulation. Then, after an error correction processing is performed,the program stream header detector 71 obtains data information thatfollows the header.

[0300] Further, the PES packet header detector 72 detects, for example,address information for each picture described in the private 2 packetof the PES packet and address information of the data for the specialplayback and the information is stored in the address memory 75. Here,the PES packet for the audio, the PES packet for such as characters orthe like and the PES packet for the video are classified so that onlythe packet for the video is outputted to the video bitstream generator73.

[0301] Here, the video bitstream generator 73 erases added informationfrom the PES packet and constructs a bitstream. Specifically, the datasuch as each kind of control code and the time stamp is eliminated.After this, in accordance with the address information obtained from theaddress memory 75, with the output of the mode switcher 76, thebitstream is rearranged at the time of the normal playback by the datarearranger 74.

[0302] The output (control signal) of the mode switcher 76 is suppliedto the data rearranger 74 and the decodable determiner 84. The datarearranger 74 either reconstructs the data before the division from thelow-frequency component and the high-frequency component divided andhierarchized by obtaining the control signal. Otherwise, only thelow-frequency component is outputted to the variable-length decoder 77.In other words, each of the low-frequency components is synthesized withthe high-frequency component at the time of the normal playback so thatthe device is operated in such a manner that the data is rearranged inan order of the original picture. At the time of the special playback,either the low-frequency component only of the I picture or thelow-frequency component of the I picture and the P picture is outputteddepending on the high-speed times.

[0303] At the time of the special playback that allows the passage onlyof the low-frequency component, the time stamp is not used. In contrast,the variable-length decoder 77 extracts the boundary of the events inthe low-frequency component area designated by the priority break pointsof the slice header together with the decodable determiner 84 so thatthe data is decoded up to the boundary and is outputted to the switch78. This switch 78 is connected so that zero is not inserted at the timeof the normal playback. In the meantime, at the time of the specialplayback, the switch 78 is controlled with the decodable determiner 84so that zero is inserted into the high-frequency component area afterthe priority break point at the time of the special playback.

[0304] The aforementioned operation will be explained with respect toFIG. 44. Referring to FIG. 44, when the partitioning breaking point isE1 through E3, E1 through E3 is stored in the stream of thelow-frequency component. E4 through EOB are stored in the stream of thehigh-frequency component. In the stream of the low-frequency component,the low-frequency component data in the subsequent DCT block followingE3 is stored.

[0305] Here, at the time of the normal playback, the data rearranger 74extracts the data E1 through E3 from the low-frequency component streamand the data E4 through EOB from the high-frequency component stream.Further, the data rearranger 74 extracts the data respectively toreconstruct the DCT data in sequency. In contrast, at the time of thespecial playback, the data rearranger 74 extracts the data E1 through E3followed by variable-length decoding by the variable-length decoder 77,the decodable determiner 84 detects the priority break point so thatzero is inserted into a portion provided with a hatching shown in FIG.44 to constitute a DCT block by using only a low-frequency component.

[0306] The data which is converted into the DCT block is decoded inaccordance with the motion vector. Here, an explanation of the decodingby the motion vector will be omitted because the decoding is the same asthe conventional example. However, the reference used in the decoding ofthe P picture at the time of the special playback is decoded by usingthe I picture or the P picture which is decoded only with thelow-frequency component.

[0307] The data which is decoded in the unit of block is inputted to theframe memory 83. Here, the frame memory 83 restores the picture in theoriginal order of the structure of the GOP, and outputs through theconversion from the block scan to the raster scan. Incidentally, theframe memory 83 can be commonly used with the memory incorporated in theprediction data decoding circuit 82.

[0308] The coding area is defined at the boundary of the events, but itgoes without saying that the definition of the boundary can be made byother methods. In other words, the high efficiency coded data of thepicture may be divided either with the quantization or the division ofthe space resolution in addition to the division of the frequency area.

[0309] At this time, data more important as a picture is data of thelow-frequency area in the case of the frequency division. In the case ofthe division of the quantization, the data refers to data coded by arough quantization. In the case of the data divided with the spaceresolution, the data refers to the data obtained by coding the thinnedpicture. In this case, in the playback picture decoded by using onlythese data items, the area which can be easily perceived by men isdefined as important data. In other words, one high efficiency codeddata is divided into basic and important data and data which is not soimportant (this process is referred to as hierarchization) so that onlybasic and important data can be played back at the time of the specialplayback when the data is played back from the disc.

[0310] Embodiment 9 describes a case in which the recording sidecorresponds to the playback side. It is also considered that in the casewhere the record and the playback is combined in a set such as a harddisc or the like, only the playback side is considered on thepresupposition that the data is recorded in accordance with the conceptof the conventionally available compact disc or the like.

[0311] Embodiment 10

[0312] Next, embodiment 10 of the present invention will be explained.FIG. 46 is a block diagram showing a record system of the digital videosignal record and playback device according to embodiment 10 of thepresent invention. Like numerals in FIG. 46 denote like parts orcorresponding parts in FIG. 37. Reference numeral 65 denotes an inputterminal, 51 a buffer memory, 52 a subtracter, 53 a DCT circuit, 54 aquantizer, 56 an inverse quantizer, 57 an inverse DCT circuit, 58 anadder, 59 a motion compensation predicting circuit, 55 a variable-lengthencoder, 62 an area rearranger, and 61 a format encoder.

[0313]FIG. 47 is a block circuit diagram showing a playback system of adigital video signal record and playback device according to embodiment10 of the present invention. Like numerals in FIG. 47 denotes like partsor corresponding parts in FIG. 43. Reference numeral 71 denotes aprogram stream header detector, 72 a PES packet detector, 73 a videobitstream generator, 85 an area rearranger, 75 an address memory, 76 amode switcher, 77 a variable-length decoder, 79 an inverse quantizer, 80an inverse DCT circuit, 81 an adder, 82 a prediction data decodingcircuit, and 83 a frame memory.

[0314] Next, an operation of embodiment 10 will be explained. Thedigital video signal is inputted in the unit of line from the inputterminal 65, and is supplied to the buffer memory 51. Here, an operationfrom the buffer memory 51 to the variable-length encoder 55 is the sameas the aforementioned example, and an explanation thereof will beomitted.

[0315] The area rearranger 62 rearranges data with respect to the Ipicture in a bitstream of video data outputted in the unit of GOP fromthe variable-length encoder 55, so that an area located at the centralpart of the screen is arranged at the front of the bitstream. Here, theI picture is divided into three areas as shown in FIG. 48. The data ofthe I picture corresponding to the areas 1 through 3 are defined asI(1), I(2), and I(3). However, each area shown in FIG. 48 is acollection of a plurality of MPEG slice layers. In FIG. 48, the area 1and 3 consists of six slices and the area 2 consists of 18 slices.

[0316] In actuality, the area rearranger 62 detects the slice header ofthe I picture on the bitstream and classifies each slice into threeareas shown in FIG. 48 thereby forming a bitstream for each of the areasfor rearranging the bitstreams arranged for each of the areas. In otherwords, as shown in FIG. 49, the bitstreams are rearranged in the unit ofarea so that the bitstream is arranged in the order of I(2), I(3) andI(1) at the front of the GOP. Further, the rearranged bitstreams areoutputted to the format encoder 61 in the unit of GOP.

[0317] Next, an operation of the format encoder 61 will be explained inaccordance with FIG. 50. FIG. 50 is a flowchart showing an algorithm forformatting the video data into the PES packet in the unit of GOP. In thecase of the screen central part priority mode, the picture header of thebitstreams to be inputted is detected and the picture information isdetected. Here, in the case of the I picture, the central parts of thescreen I(2), I(3) and I(1) shown in FIG. 49 are extracted and respectivedata lengths are detected so that the data length of each area thusdetected is converted into a binary number of 24 bit width therebypreparing an address information. On the other hand, the data lengthsare detected in the unit of picture with respect to the P picture andthe B picture so that the data lengths are converted into a binarynumber of 24 bit (3 bytes) width thereby preparing address information.

[0318] Further, the formatting unit collects the input addressinformation and the bitstreams of the video data into two kinds of thePES packets. In other words, the PES packet having only the addressinformation and the PES packet having only the audio are constituted.

[0319] Consequently, when one GOP consists of 15 frames as shown in FIG.6, there are 17 kinds of pictures as the address information, such asthree kinds of I pictures, four kinds of P pictures, 10 kinds of Bpictures. Further, as address information at the time of the specialplayback, there are two kinds of address information of the precedingand succeeding GOP on the disc (absolute addresses on the disc) Theseitems of the address information are collected in one packet and areformatted as the PES packet. In actuality, these items of addressinformation are collected in one packet and are formatted as a private 2packet of the PES packet shown in FIG. 51. In FIG. 51, the absoluteaddress on the preceding and succeeding GOP on the disc is arranged atthe front of the packet data. Then, the address information of eachpicture is arranged in order. However, since 3 bytes (24 bits) longinformation is assigned to each address information, the packet has alength of 57 bytes.

[0320] In the meantime, with respect to one GOP portion of bitstreamsother than the address data, the bitstreams are formatted into PESpackets (video packets) by dividing the bitstreams into a plurality ofpackets and adding header information such as synchronous signals or thelike.

[0321] In addition, the format encoder 61 divides the bitstreams of theinputted audio data into PES packets to constitute an MPEG2-PS systemstream together with the PES packets of the video data. In actually, asshown in FIG. 52, the bitstreams of one GOP portion of the video dataand the bitstreams of the audio data are divided and arranged into aplurality of packets in one pack. In this case, a packet representativeof the aforementioned address information is arranged at the frontpacket of the system stream as shown in FIG. 52. Subsequently, thedevice is constituted in such a manner that the packet containing thebitstream at the central part of the screen of the I picture isarranged.

[0322] Next, an operation at the time of the playback will be explainedwith respect to FIG. 47. In FIG. 47, since an operation of the programstream header detector 71, the PES packet header detector 72, the videobitstream generator 73 and the mode switcher 76 is the same asconventional examples, an explanation thereof will be omitted.

[0323] In the decoded video bitstreams, the data at the central part ofthe screen of the I picture is located at the front of the bitstream.Consequently, the area rearranger 85 rearranges the I picture data inthe order of I(1), I(2) and I(3) for each area in accordance with thedata length of bitstreams of I(2), I(3) and I(1) which is outputted fromthe address memory 75. The rearranged bitstreams are inputted to thevariable-length decoder 77 to be decoded into the block data, the motionvector or the like. Here, since an operation which follows thevariable-length decoding at the time of the normal playback is the sameas conventional examples, an explanation thereof will be omitted.

[0324] In a high speed playback, since one GOP portion of data isassigned to one pack of a system stream as described above, there isconsidered a method by which an optical head jumps to the front addressof each GOP when reading data from a disc to read only the data of the Ipicture which is arranged at the front of the system stream so that theoptical head jumps to the front of the subsequent GOP. In such a case,the PES packet is detected which has a record of address informationarranged at the front of th system stream to control the disc drive bydecoding the address on the disc of the subsequent GOP and the addressinformation of the I picture.

[0325] In the case shown in FIG. 6, when all the I pictures in each GOPcan be read within one frame, a 15 times high-speed playback can berealized. When the I pictures in each GOP are read within 2 frames, a7.5 times high-speed playback can be realized. In this manner, when thehigher speed of playback can be realized, time for reading data from thedisc becomes shorter.

[0326] Further, in the case where data is read from the recording mediumsuch as an optical disc or the like, even if the front address is known,there arises disc rotation waiting time at the time when the opticalhead jumps to a location of the disc where the data is actuallyrecorded. Further, when the video signal is coded with a variable rate,the amount of information of the I picture is not definite and timerequired for reading the I picture also varies. Consequently, when thespeed in the high-speed playback becomes higher, time for reading dataon the disc becomes shorter. Further, since the waiting time for thedisc rotation is not definite, it becomes impossible to read stably thewhole data of the I picture.

[0327] Consequently, in embodiment 10, the optical head jumps to thefront of the GOP in the unit of a definite time with respect to the datarecorded in the unit of GOP on the recording medium such as an opticaldisc or the like at the time of the high-speed playback. Thus the datapart of the I picture is read from the disc. In this case, even if thewhole data of the I picture cannot be read, the optical head jumps tothe front of the subsequent GOP. In other words, the optical head jumpsto the front address of each GOP in the unit of a certain time to readdata as much as possible from the front of the system stream and thenjumps to the front of the subsequent GOP.

[0328] In this case, the PES packet including the address on the disc orthe like of the subsequent GOP and the PES packet including the data atthe central part of the I picture are arranged at the front part of thesystem stream. Consequently, even in the case where the whole data ofthe I picture can not be read at the time of the special playback, atleast the address on the subsequent GOP disc and the data at the centralpart of the I picture can be decoded, the address and the data beingrequired for controlling the disc drive.

[0329] In the case where only the central part of the screen can bedecoded at the time of the special playback, only the data which can bedecoded by the area rearranger 85 is outputted to the variable-lengthdecoder 77 so that the variable-length decoded video data is inputted tothe frame memory 83 through the inverse quantization and inverse DCT. Inthe meantime, the area rearranger 85 inputs the area information whichcannot be decoded into the frame memory 83. With respect to the areawhich cannot be decoded, the data outputted in the preceding frame isheld as it is and is outputted.

[0330]FIG. 53 shows one example of playback picture in the case where ahigh-speed playback is performed by playing back only the I picturesfrom the nth GOP to the n+4th GOP. FIG. 53A shows a case in which thewhole I picture can be decoded. FIG. 53B shows a case in which areas 2and 3 can be decoded. In the area 1 which cannot be decoded, the valuein the preceding frame is held as it is and outputted. In addition, FIG.53C shows a case in which only the area 2 can be decoded. In the areas 1and 3, the value in the preceding frame is held as it is.

[0331] Here, in the general video signal record and playback device, aformat is adopted in which the I picture is recorded in the unit offrame at the time of recording. In contrast, in FIG. 52, the arealocated at the central part of the screen out of the I picture datawhich is divided into three parts is arranged at the front of one GOP bygiving a priority to the area. Consequently, even in the case where thearea of only part of the I picture can be read from the disc in adefinite time at the time of the special playback, the playback pictureat least at the central part of the screen can be outputted.

[0332] As described above, in embodiment 10, as shown in FIG. 52, withrespect to the I picture for use in the special playback, data of thearea located at the center of the screen is arranged at the front of oneGOP so that the area is given a priority to be recorded on the recordingmedium so that the area 2 located at the central part of the screen isgiven a priority to be played back even when the speed in high-speedplayback is high so that the content of the high speed playback pictureis easy to see. Further, the special playback is performed in which theoptical head jumps to the front of the GOP in the unit of a definitetime with the result that an output screen can be renewed at apredetermined high-speed.

[0333] Incidentally, the aforementioned embodiment may be constituted sothat data of an area that can be decoded at the time of the specialplayback is all outputted, and for the area whose data cannot bedecoded, the data of the preceding frame is held as it is. However onlythe central part of the screen may be played back at the time of thespecial playback.

[0334] In this case, the area rearranger 85 decodes the data only of thearea of the I picture which is read from the disc. With respect to theareas 1 and 3 whose data is not decoded, for example, it is masked by agray data to output a high speed playback picture at the frame memory83.

[0335]FIG. 54 shows a playback picture in the case where only the area 2of the I picture from the nth GOP to the n+4th GOP is played back forthe high speed playback. In FIG. 54, the areas 1 and 3 on both ends ofthe screen in FIG. 54 are masked by gray data. Further, even in the casewhere the information amount of the I picture is small, the waiting timefor the disc rotation is short, and sufficient time is available forreading the data of the areas 1 and 3, the data of the areas 1 and 3 arenot decoded.

[0336] This is because the high speed playback picture becomes unnaturalif the data of the areas 1 and 3 are outputted on the screen only whenthey can be read, and the areas 1 and 3 are not renewed in a certaininterval. Consequently, when only the central part of the screen of theI picture is played back at the time of the special playback, the areato be renewed becomes constant so that the playback picture becomes freefrom unnaturalness.

[0337] Further, in the aforementioned embodiment, only the area of thecentral part of the I picture which can be decoded at the time of thespecial playback is displayed to mask both ends of the screen. However,the central part of the screen may be extended to a size of one screenand outputted.

[0338] In this case, in the frame memory 83, the data of the decodedarea 2 is extended to a size of one screen as shown in FIG. 55. However,in the case of FIG. 55, the central part (FIG. 55A) of the area 2surrounded by a dot line is extended to double the size by linearinterpolation in the horizontal and vertical directions. In other words,in the case of FIG. 55, the part surrounded by a dot line has a size ofhorizontal 360 pixels×vertical 240 lines. This dot part is extended bylinear interpolation to a size of one screen consisting of horizontal720 pixels×vertical 480 lines.

[0339] Accordingly, when only data of the area of the central part ofthe screen is decoded at the time of the special playback to extend thecentral part to a size of one screen. The area whose data is outputtedbecome small. In this way, however, the masked part at the both ends ofthe screen which is conspicuous when only the central part of the screenis outputted can be eliminated.

[0340] In the aforementioned embodiment, only the central part of thescreen of the I picture is given priority to be arranged on thebitstream. However, another constitution is also possible in which thecentral part of the screen of the P picture as well as that of I pictureare given priority. In this case, the data of the central part of thescreen of the P picture is arranged after the bitstream of the Ipicture.

[0341] In the aforementioned embodiment, the picture data is rearrangedin the unit of area after the data is converted into the bitstreams.However, the picture data may not necessarily be rearranged after thedata is converted into the bitstreams. The picture data may berearranged before the data is converted into the bitstreams.

[0342]FIG. 56 shows a flowchart of the playback side of embodiment 10.The procedure of the flowchart is already described above and is omittedhere.

[0343] Embodiment 10 is described by corresponding the recording sidewith the playback side. There is also considered a case in which therecord and playback constitute a pair like a hard disc. There is alsoconsidered a case where the playback side on a presupposition that datais recorded in accordance with the supposition like a current compactdisc. Further, it goes without saying that the data rearrangement of thescreen in the unit of area can be realized in the prediction datadecoding circuit 82 and the frame memory 83 by using the data of thelower 8-bit long slice vertical position of the slice start code in theslice head.

[0344] Embodiment 11

[0345] Next, embodiment 11 of the present invention will be explained.FIG. 57 shows a digital video signal coding processing unit in a digitalvideo signal record and playback device wherein the DCT block ishierarchized into a low-frequency are and a high-frequency area.Further, FIG. 57 is a block diagram on the recording side in which thescreen is divided into a plurality of areas so that the central part ofthe screen of the low-frequency area is given a priority to be arrangedat the front of the GOP. In FIG. 57 reference numeral 62 denotes an arearearranger. Like parts and corresponding parts in FIG. 57 are denoted bylike numerals and an explanation thereof will be omitted.

[0346] Next, an operation of the device will be explained. This videodata to be inputted includes an effective screen size with horizontal704 pixels×vertical 480 pixels. The motion compensation and the DCT areused to apply high efficiency coding to the picture data. Here, theoperation up to the data division and hierarchization is the same asembodiment 9, and an explanation thereof will be omitted.

[0347] Embodiment 11 is the same as embodiment 9 in that the data may bedivided with the quantification and space resolution as well as with thefrequency area with respect to the division hierarchization. Inembodiment 11, important data further divided and hierarchized with thedata rearranger 62 is divided for each area of the screen as shown inembodiment 10 so that the central part of the screen is given a priorityto be arranged at the front of the GOP. In other words, the data isdivided into important data and data which is not important so that thedata is recorded on the disc in the priority order which ispreliminarily determined in an area.

[0348] In this manner, the low-frequency components of the I picture andthe P pictures are divided so that the central part of the screen isgiven a priority in the arrangement. When only the central part of thescreen of these low-frequency components are read and played back at thetime of the special playback, the data amount which is read at the timeof special playback will be largely decreased. Consequently, anallowance can be made for the reading speed from the recording medium sothat an extremely fast skip search can be actualized at a speed of morethan ten times speed or tens of times speed.

[0349] Here, the central part of the screen of the low-frequency of thescreen is arranged at the front of the GOP, and the data of the Ppictures are arranged following the data of the peripheral part of thescreen in the low-frequency area of the I picture with the result that ahigh-speed playback can be realized at more than ten times speed or tensof times of speed by playing back only the central part of the screen inthe low-frequency of the I picture. Further, the central part of thescreen for the low-frequency component of the I picture and the Ppicture for the special playback has a small amount of data so that thedata in the central part of the screen can be easily read and decodedfrom the disc. Thus a high-speed playback can be realized at severaltimes speed. In other words, since the data amount at the central partof the screen for the low-frequency component of the I picture and the Ppicture has a smaller amount of data than that of entire low-frequencycomponent, the special playback can be realized at a speed faster thanembodiment 9.

[0350] Next, an operation of the area rearranger 62 and the formatencoder 61 will be explained. FIG. 58 is a flowchart thereof. In thebeginning, when the encoding is started, the slice header of the Ipicture of the low-frequency component partition is detected so thateach slice is classified into three areas shown in FIG. 48. Thenbitstreams for each area are prepared for rearranging the bitstreamscollected for each area. In other words, the data is rearranged for eacharea so that the bitstreams are arranged in the order of a low-frequencyarea I(2), a low-frequency area I(3), and a low-frequency area I(3) atthe front of the GOP with respect to the low-frequency area I picturelike FIG. 49.

[0351] Then, in the case of the screen central part priority mode, thepicture header of the bitstreams to be inputted is detected to detectthe picture information. Here, in the case of the low-frequency area Ipicture, the central part I(2) of the low-frequency area screen, thelow-frequency area I(3) and the low-frequency area I(1) are extracted todetect the data length thereby preparing address information from thedata length of each area. In the meantime, in the case of the P pictureand the B picture the data length is detected in the unit of picturethereby preparing address information. In modes other than the screencentral part priority mode, the operation follows embodiment 9.

[0352] Next, the hierarchical mode is judged. In modes other than thehierarchical mode, information is inserted into the system streams whichrepresents that the mode is non-hierarchical thereby following thestructure of the conventional streams. In the case of the hierarchicalmode, the setting of the sequence header is confirmed. Specifically, thedata of the sequence scalable extension is confirmed. In the case wherethe data is correctly described, the front of the picture is recognizedwith the picture header so that the low-frequency area data in the Ipicture and the P picture rearranged in the screen area is extracted andthe data length is detected. In the meantime, the data length of the Bpicture is detected for each picture.

[0353] Further, a packet is prepared wherein only address information isrecorded in the case where the screen central part of the low-frequencyarea of the I picture and the P pictures is collected at the front ofthe GOP. This packet includes the screen central part of thelow-frequency area part of the I picture and the P picture, theperipheral part of the screen, the high-frequency area part of the Ipicture and P pictures, and address information of the B picture so thatthe data length of respective data is recorded. Consequently, the frontposition of respective data streams are obtained as relative addresswith respect to the front of the GOP header.

[0354]FIG. 59 shows bitstreams prepared in this manner. As shown in FIG.59C, the low-frequency areas of the I picture and the P picturesrearranged in the unit of area are arranged at the front of the GOP.Consequently, FIG. 59D shows a case in which the rearranged data oflow-frequency areas are packetted so that the address information isarranged in the private 2 packet as shown in the flowchart of FIG. 58.In this case, the address information may be represented with a relativeaddress with respect to the front of the GOP head as described above.Otherwise, the address information may be represented in such a mannerthat which byte of which packet falls on the front of each picture. Itgoes without saying that the address information may be represented witha sector address on the disc in addition to it.

[0355]FIG. 60 shows an example in the case where the address informationis contained in the private 2 packet. In the case where the PES packetis adopted as the private 2 packet, the stream ID is set, so that thehierarchical mode, the kind of hierarchization, the kind of picture usedat the time of the special playback and the number of start addressesare described. Here, the start address refers to the start address ofthe screen central part of the low-frequency area of the I picture, thestart address of screen peripheral part of the low-frequency area of theI picture, the start address of the remaining B picture.

[0356] Further, a sector address of the preceding and succeeding GOP onthe disc is added for allowing the optical head to jump at the time ofthe special playback. In this case, when the sector address of theseveral front and rear GOP is further added in addition to the addressof the preceding and succeeding GOP in consideration of the high-speedtimes at the time of the special playback, the variation of high-speedtimes of the special playback will be widened. Further, it is shown thatthe address information is described in the private 2 packet of the PESpacket. It goes without saying that the address information may bedescribed in the private descripter of the program stream map, otheruser areas or the like.

[0357] The playback side of the device in embodiment 11 will bedescribed in accordance with FIG. 61. FIG. 61 is a block diagram of thedigital video signal decoding unit. Like parts or corresponding parts inthe figure are denoted by like numerals, and an explanation thereof willbe omitted.

[0358] Next, an operation of FIG. 61 will be explained in accordancewith FIG. 62. FIG. 62 is a flowchart showing an operation of the formatdecoder at the time of the playback. The bitstream outputted from theECC is detected the header of the program stream and is separated foreach of the PES packet. Further, the bitstream is detected the header ofthe PES packet to differentiate the private packet containing theaddress information and the video packet.

[0359] In the case of the private packet, the address informationcontained in the packet is extracted and stored. In the meantime, in thecase of the video packet, the bitstreams of the video packet isextracted. Further, in the case of the private packet and normalplayback, or in the case of the video packet, the data of thelow-frequency component and the high-frequency component is extractedfrom the bitstreams of the video data of the I picture and the Ppictures so that the data is rearranged for outputting a playbackpicture.

[0360] In the meantime, in the case of the private packet and thespecial playback, it is judged in the beginning whether or not time isavailable for playing back the whole low-frequency I pictures In thecase where time is available for the playback, it is further judgedwhether time is available for playing back the low-frequency P pictures.The aforementioned two or one judgements are made. Thus, in the casewhere time is available for playing back the low-frequency I picture andP pictures, the I picture and the P pictures are played back. In thecase where time is available for playing back the whole low-frequency Ipicture but time is not available for playing back the low-frequency Ppictures, only the low-frequency I picture is played back. Further, inthe case where time is not available for playing back the whole Ipicture, the central part of the screen of the low-frequency I pictureis played back. In the aforementioned three cases, the optical head isallowed to jump to the front of the next GOP.

[0361] In the case where these addresses are described in thebitstreams, the address information is extracted and stored after thebitstreams are formed. In the case where these addresses are describedin the private descripter of the program stream map, the addressinformation is extracted and stored at the level of detecting theprogram stream header. It goes without saying that the addressinformation may be either relative address of the program or theabsolute address of the program.

[0362] In actually, as shown in FIG. 61, the mode signal for skipsearch, normal continuous playback or the like is inputted to the modeswitcher 76 from the microcomputer. In the meantime, the playback signalfrom the disc is amplified by an amplifier and the signal is played backwith a clock which is outputted from a PLL and in which the phase issynchronized. Then, the signal is digitally modulated and an error iscorrected to restore a program stream. Further, information is obtainedas to the data which follows the header by the program stream headerdetector 71 for detecting each head of the program stream.

[0363] Further, the address information for each picture and specialplayback data (low-frequency data and data arranged by the area of thescreen) which are described in the private 2 packet of the PES packet isdetected by the PES packet header detector 72 and the information isstored in the address memory 75. Here it is judged whether the PESpacket is an audio PES packet, a PES packet such as characters, or avideo PES packet so that only the video PES packet is outputted to thevideo bitstream generator 73. The video bitstream generator 73eliminates the header removal of the PES packet to output thebitstreams. After this, in accordance with the address informationobtained from the address memory 75, the data rearranger 74 rearrangesthe bitstreams outputted from the mode switcher 76 and outputs thebitstreams in the normal playback.

[0364] The output (control signal) from the mode switcher 76 is suppliedto the data rearranger 74 and the decodable determiner 84. Here, thedata rearranger 74 synthesizes the low-frequency component and thehigh-frequency component hierarchized and rearranged for each of theareas and outputs the synthesized components. In the meantime, eitherthe data only of the low-frequency component or the data only of thelow-frequency components at the central part of the screen are outputtedto the variable-length decoder 77 at the time of the special playback.In other words, at the time of the normal playback, the low-frequencycomponents of the I picture and the P pictures are rearranged in theorder of areas on the screen. Then the low-frequency components aresynthesized with the high-frequency components so that the device isoperated to rearrange the data in the original order of pictures. At thetime of the special playback, the area of the low-frequency componentsof the I picture at the central part of the screen and the area of thelow-frequency components of the I picture and the P picture at thecentral part of the screen are switched over to be outputted. The timestamp of the PTS and the DTS are not used at the time of the specialplayback which uses only the low-frequency components.

[0365] In contrast, the variable-length decoder 77 extracts the boundaryof the events in the low-frequency components region denoted by thepriority break point of the slice header together with the decodabledeterminer 84 so that the data up to the boundary is decoded to beoutputted to the switch 78. The switch 78 is connected so as not toinsert 0 at the time of the normal playback. At the time of the specialplayback, the switch 78 is controlled by the decodable determiner 84 sothat 0 is inserted into the high-frequency components after the prioritybreak point.

[0366] An operation concept of the decoding of the low-frequency is thesame as FIG. 44. An explanation thereof will be omitted. Further, atthis time, the rearrangement on the screen area is the same as explainedin embodiment 10. An explanation thereof will be omitted.

[0367] The coding area is defined at the boundary of the events, but itis needless to say that the boundary of the events may be defined byother methods. For example, the coding area may be divided by the end ofa predetermined number of events, or the coding area may be defined bydividing the data by the data subjected to a rough quantization by thequantizer 54, and a differential value between the rough quantizationand a fine quantization. Further, the data may be divided with thecoding of the picture whose space resolution is decreased to the half bythinning and the picture whose resolution has been restored to theoriginal level from the half level and the differential picture with thepicture with the original resolution. In other words, it goes withoutsaying that the high efficiency coded data of the picture may be dividedby the division of the quantization and the space resolution in additionto the division of the frequency region.

[0368] At this time, more important data as a picture refers to the datain the low frequency region in the case of the frequency division. Inthe division of by the quantization, the more important data refers tothe data coded by the rough quantization. In the case of the datadivided by the space resolution, the more important data refers to thedata obtained by coding a thinned picture. In such a case, with respectto the playback picture decoded by using only these items of data, aregion which can be easily perceived by man constitutes the moreimportant data. In other words, one high efficiency coded data isdivided into more basic and more important data and the data which isnot important so that the data which is basic and important is playedback at the time of the playback from the disc.

[0369] Embodiment 11 is described by corresponding the recording side tothe playback side. There may be a case where record and playbackconstitute a pair like a hard disc. Further, a case is consideredwherein only the playback side is given on a supposition that the datais recorded in accordance with the presupposition like compact discs.Further, with respect to the component rearrange for each of the areasof the screen, it goes without saying that a method for outputting ascreen as shown in FIG. 54 and FIG. 55 in embodiment 10 is available.Further, it goes without saying that the rearrangement in the unit ofarea on the screen can also be realized with the prediction datadecoding circuit 82 and the frame memory 83 when the data of the slicevertical position in the slice header. Further, in embodiment 11, onlythe basic data of the I picture is divided by the area of the screen. Itis needless to say that the data may be divided with the low-frequencyof the P picture or others.

[0370] Embodiment 12

[0371] Embodiment 12 of the present invention will be explained withrespect to FIG. 63. FIG. 63 is a block diagram showing a digital videosignal coding processing unit in a digital video signal record andplayback device. In FIG. 63, reference numeral 101 and 104 denotepreprocessors, 102 and 105 motion vector detectors, 103 a resolutionconverter, 106 and 107 subtracters, 108 and 109 DCT circuits, 110 and111 quantizers, 112 and 113 variable-length encoders, 114 and 115inverse quantizers, 116 and 117 inverse DCT circuits, 118 and 119adders, 120 and 121 image memories, 122 and 123 rate controllers, 124 aresolution inverse converter and 125 a data reconstructor as a dataarranging means. Further, FIG. 63 shows a first encoding means and asecond encoding means as one example. In particular, the subtracter 106outputs a differential component between the first encoding means andthe second encoding means in the course of two coding.

[0372] Next, an operation of embodiment 12 will be explained. The videodata is inputted to the resolution converter 103 in an order of theraster scan of the interlace. The inputted video data is filtered andthinned for preventing repetitive noises in the high-frequency regionwith the resolution converter 102. FIG. 64 is an explanatory viewexplaining the concept of this resolution conversion on the picture. Forexample, in the case of the data of horizontal 704 pixels and vertical480 pixels, the data is filtered followed by being thinned intohorizontal 352 pixels and vertical 240 pixels with a half resolutionthereof respectively thereby being converted into a low resolutionscreen data.

[0373] This low resolution screen data is converted from a raster scaninto a block scan by being inputted into the preprocessor 104. Here, theblock scan means that the data is sent in an order of the block of DCT.The I picture is coded without performing a calculation between framesusing the output of the frame memory for intra-frame coding.

[0374] In the case of the I picture, the image memory 121 which is aninput of the subtracter 107 outputs nothing so that the video signalpasses through the subtracter 107. This data is orthogonally convertedinto the frequency component by the DCT circuit 109. This orthogonallyconverted data is inputted into the quantizer 111 and quantized in anorder of being scanned in a zigzag manner from the low frequency region.Further, the quantized picture data is converted into an entropy codevia the variable-length encoder 113 to be outputted to the datareconstituting device 125.

[0375] In the meantime, the data quantized by the quantizer 111 issubjected to the inverse quantization with the inverse quantizer 115.Then, the picture data is inversely converted into data of a spacecomponent from a frequency component data by the inverse DCT circuit117. The I picture is decoded without calculation between framesperformed by using the output of the frame memory which is subjected tothe intra-frame coding. Consequently, in the case of the I picture,since there is no input from the image memory 121 of the adder 119, thedata passes through the adder 119. An output of the adder 119 is used asdata stored in the picture memory 121. At least, the I picture data, orthe I picture data and the P picture data is required to be stored inthe picture memory. That is because the data of I picture and P pictureis needed for decoding the B picture normally at the MPEG1 and MPEG2 asreference data.

[0376] Further, the image memory 120 inputs the output from the adder118 of the decoded data and the result of the restored number of pixelsby interpolating the pixel by the resolution inverse converter 124 tostore the decoded data of the picture averaged with a certain weight.With respect to this weighting, there is described a case in which aweight of 1 is used as the output of the resolution inverse converterand a weight of 0 is used as the output of the adder 118 for simplicity.

[0377] Further, the input video data is buffered by the preprocessor 101to be scan-converted from the raster scan to the block scan. Then, thevideo data is subtracted by the subtracter 106 from the data of theimage memory 120 which stores a signal subjected to the aforementionedlow resolution processing (this is referred to as resolution residualcomponent). The resolution degree residual component is orthogonallyconverted into a frequency region to be converted into the scan from thelow-frequency region to be appropriately quantized by the quantizer 110.This data is coded into an entropy coded via the variable-length encoder112 and is outputted to the data reconstructor 125.

[0378] In the meantime, the data quantized by the quantizer 110 isinversely quantized by the inverse quantizer 114 and is inverselyconverted in the data in the space region at the inverse DCT circuit116. The adder 118 adds the input from the image memory 120 which is theinversely converted data subjected to the low resolution processing withconverted data with the output of the inverse DCT circuit 116 to obtainthe result of decoding of the data which is formed into two layers withthe low resolution data and the data of the residual component as oneexample of the data other than the low resolution data. This layer isdetermined by the frequency of resolution conversion. It is possible toform the layer into three layers by performing two resolutionconversions. In the same approach, it is possible to prepare data in anynumber of layers with the similar approach.

[0379] With respect to coding of the normal MPEG, the I picture and theP picture are decoded and stored as a decoded data to code the B pictureby performing a bidirectional prediction with the I picture and the Ppicture. In this manner, the I picture and the P picture are codedfollowed by the processing of the B picture.

[0380] The aforementioned coding processing of the I picture, P picturesand B picture are performed with respect to both the low resolutioncomponent and the high resolution component. In this manner, a sequencecan be constituted wherein the low resolution component R (hereinafterreferred to as R component) and the resolution residual differencecomponent S are arranged side by side. The operation is performed by thedata reconstructor 125 so that the data is arranged at a place such asthe front of the GOP to which the optical head can favorably access. Forexample, the data is arranged as shown in sequence a of FIG. 65. Whenthe data is rearranged as shown in FIG. 65 and the half of the areawhich is occupied by the L component, the low resolution component canbe played back. The resolution residual difference component has asmaller data amount than the non-resolution residual differencecomponent, and the data can be efficiently hierarchized. In other words,here, a first encoding means for coding in accordance with predeterminedconditions and a second encoding means for coding the residualdifference of coding using the first encoding means as an example of avideo information other than coded by the first encoding means out ofvideo data are provided for an efficient hierarchization.

[0381]FIG. 65 is a view showing an example of the result of dataconstitution. In FIG. 65, a sequence a is a sequence generated by thecoding processing of embodiment 12. A sequence b is a sequence generatedby the coding processing in another embodiment. A sequence c is asequence generated by the coding processing in further anotherembodiment. In the sequence b, symbol L denotes a low frequencycomponent, and H a high frequency component. In the sequence c, symbol Cdenotes a component coded by a rough quantization, and A a residualcomponent by the rough quantization, respectively. As shown in thesequence a in FIG. 70, the aforementioned operation is performed withrespect to only the I picture and P pictures. Only the component may bearranged in summary at the front of the GOP.

[0382] In this manner, when only the low resolution component isarranged in summary at the front of the GOP, the ratio of the Lcomponent occupying the whole largely reduces so that an allowance canbe made in the reading speed from the medium so that the skip search canbe easily realized. In addition, like a sequence a, when only the Rcomponent of the I picture and the P picture are arranged in summary atthe front of the GOP, the operation is performed so that only the lowresolution data of the I picture and the P picture are decoded. In theaforementioned embodiment, an explanation is given to a case in whichthe thinning ratio is horizontal ½ times, and vertical ½ times. It goeswithout saying the ratio can be set to a value different from theaforementioned value, but an arbitrary ratio can be applied to theembodiment.

[0383] Further, the coding mode includes the MPEG1, MPEG2 and JPEG orthe like. In the hierarchization of the resolution, a common codingtechnique is not necessarily adopted. That is because when the data iscoded by lowering the resolution, it is possible to sufficientlycorrespond to the coding with the MPEG1 mode. In addition, in the JPEGmode, the lamination of one frame on another constitutes a mobilepicture. Consequently, it is possible to decode correctly the data evenwhen the data occupies a specific position of the GOP. In addition, theexplanation is given with respect to two degrees of resolution, but isgoes without saying that larger number of hierarchies can be used. Thedifferential component may be coded in the following manner: the data ofthe low resolution component is coded with the first encoding means inFIG. 63; the output from this first encoding means is interpolated; thedifferential component with the picture before thinning the pixels andthe interpolated data is obtained with the subtracter 106; and thedifferential component is coded by a differential component encodingmeans.

[0384] The frame read from the image memory is normally brought from theprediction reference frame. With the existence of the low resolutionframes, the data is required to be stored in the memory (including thememory address) by favorably adjusting the time axis. It goes withoutsaying that an information adding means may be provided to addadditional information such as an audio signal, a header or the like,and an error correction signal to the differential component.

[0385] Embodiment 13

[0386] Embodiment 13 of the present invention will be explained on thebasis of FIG. 66. In embodiment 13, the DCT block is divided into thelayers of a low-frequency region and a high-frequency region so thatonly the low frequency region is arranged at the front of the GOP. FIG.66 is a block diagram of the digital video signal coding processingunit. In FIG. 66, reference numerals 126 and 127 denote firstvariable-length encoder and a second variable-length encoder,respectively. Like parts or corresponding parts in FIG. 66 are denotedby like numerals in FIG. 63, and an explanation thereof will be omitted.

[0387] Next, an operation will be explained. This interlace video datais a data item which has, for example, an effective screen size ofhorizontal 704 pixels and vertical 480 pixels. Since the I picture isdecoded without performing calculations between frames using the outputof the frame memory subjected to the intra-frame coding, the video datais passed through and outputted. This video data is orthogonallyconverted into the frequency component by the DCT circuit 108, and isconverted into the block scan from the low frequency region. Then thevideo data is converted into a block scan from the low frequency regionto be appropriately quantized by the quantizer 110.

[0388] The data arrangement of the DCT coefficient inside of the DCTblock is shown in FIG. 67. In FIG. 67, a low frequency component islocated at an upper part on the left and high frequency component is-located at a lower part on the right. Out of the DCT coefficient dataarranged in this DCT block, the DCT coefficient data (for example, ahatched part in FIG. 67) in the low-frequency region up to the data ofthe DCT coefficient at a specific position is entropy coded via thefirst variable-length encoder 126 as a low frequency region extractingmeans and is outputted to the data reconstructor 125. Further, thesecond variable-length encoder 127 performs the variable-length codingof the data of the DCT coefficient after the data of the DCT coefficientat the aforementioned specific position. That is, in this manner, thedata is partitioned and coded in the frequency region.

[0389] With respect to the coding of the motion vector and the DCcomponent, the coding may be performed only by the first variable-lengthencoder 126. The second variable-length encoder 127 is not required.That is because at the time of the normal playback, the output data ofthe first variable-length encoder 126 and the output of the secondvariable-length encoder 127 may be synthesized and coded.

[0390] The determination of the coding region is performed at the fixedposition of the DCT coefficient. The determination can be made by othermethods. For example, the coding region may be determined with the fixednumber of events. In other words, a unit for providing a Huffman codewhich is a variable-length code is an event. The coding region may beset with a predetermined number of events such as a unit of three or thelike. In an example of the output bitstreams at the data reconstructor125 with the arrangement of sequence b in FIG. 65, the low frequencyregion picture can be played back when only the first half of thelow-frequency region is read. The coding region may be determined in avariable manner at the arrangement such as sequence b shown in FIG. 70.

[0391] In the meantime, the data quantized by the quantizer 110 issubjected to an inverse quantization. Then the data is inverselyconverted into the data in the space region by the inverse DCT circuit116. The I picture is decoded without performing the calculation betweenframes using the output of the frame memory subjected to the intra-framecoding. Consequently, in the case of the I picture, there is no inputfrom the image memory 120 of the adder 118. Consequently, the data isallowed to pass through the adder 118. The output of the adder 118 isused as data stored in the image memory 120.

[0392] At least. the I picture and the P pictures are required to bestored in the image memory. That is because the data of the I pictureand the P picture is normally required as reference data for thedecoding of the B picture normally at MPEGs 1 and 2.

[0393] When constituted in this manner, the ratio of the L componentlargely reduces so that an allowance can be made in the reading from themedium, enabling to realize a skip search. Further, as to be describedlater, when only the I picture and the P picture are arranged insummary, the device can be operated so that only the data of thelow-frequency component can be easily decoded. Since the data in thehigh-frequency region has smaller amount of data than all other regionsof data, the efficient constitution of data can be made possible thanextracting data in the low-frequency region and storing the data beforethe data in all the regions.

[0394] When the coding of the I picture is ended by allowing the Ipicture to pass through the subtracter 106, the B picture is coded inthe bidirectional prediction with the last P picture in the GOPpreceding in terms of time. The output of the preprocessor 101 and thedata from the memory of the reference frame (arrow in the drawingomitted) are compared with each other so that the motion vector isdetected and the prediction mode and the frame structure are judged. Onthe basis of the result of judgment, the data of the reference framememory in which the output of the preprocessor 101 and the data from thereference frame memory most favorably agree with each other is read asthe data in the forward direction portion and the backward directionportion from the frame memory 120. Consequently, the data read in thismanner and the output result of the preprocessor 101 of the B pictureare subjected to subtraction by the subtracter 106. (This result isreferred to as time residual component with respect to both the Ppicture and the I picture). This time residual component is subjected tothe DCT calculation so that the result is quantized and is subjected tothe variable-length coding.

[0395] Embodiment 14

[0396] Embodiment 14 of the present invention will be explained on thebasis of FIG. 68. In embodiment 14, the data is divided into the roughquantization component of the DCT coefficient and the rough residualdifference component hierarchy as an example of the data other than therough quantization component so that the rough quantization component isarranged at the front of the GOP. FIG. 68 is a block diagram showing adigital video signal coding processing unit. In FIG. 68, referencenumeral 128 denotes a subtracter and 129 an adder. Like parts orcorresponding parts in FIG. 68 are denoted by like numerals in FIG. 63,and an explanation thereof will be omitted.

[0397] Next, an operation of embodiment 14 will be explained. The inputpicture of this interlace has, for example, an effective screen size ofhorizontal 704 pixels and vertical 480 pixels. The I picture is decodedwithout performing the calculation between frames using the output ofthe frame memory which is subjected to the intra-frame coding.Consequently, in the case of the I picture, nothing is inputted to thepicture memory which is the input of the subtracter 106 with the resultthat the video signal passes through the subtracter 106. This data isorthogonally converted into the frequency component and the DCT circuit108, and is converted into the block scan from the low frequency region.Then, the quantizer 110 performs an appropriate rough quantization whichreduces the coded data amount to less than half. This quantized data iscoded into an entropy code via the variable-length encoder 112 to beoutputted to the data reconstructor device 125.

[0398] In the meantime, the data quantized by the quantizer 110 issubjected to inverse quantization (the result is referred to as theresult of the rough quantization). The data subjected to the inversequantization is sent to a different coding processing unit (part denotedby a dot line frame in FIG. 68). In the meantime, the data is inverselyconverted into the data in the space region. Here, the coding of the Ipicture is described. Although there is no output from the image memory121, in normal cases, the coding result at this coding processing unitis stored in the image memory 121 so that the data is subjected tomotion vector detection at the motion vector detector 102, theprediction mode is determined and the DCT block mode is determined. Theposition data suitable for the determined mode is referred to, and isinputted to the subtraction input side of the subtracter 107.

[0399] The output of the subtracter 107 is subjected to the DCT todetermine a residual difference (which is referred to as a roughquantization residual difference) with the result of the roughquantization and the subtracter 128. The rough quantization residualdifference is finely quantized (fine quantization on the same level asthe normal coding in consideration of the coding amount control) toperform the variable-length coding while being inversely quantized,subjected to the inverse DCT and decoded to be stored in the imagememory 121. The result of this coding and the coding result of the roughquantization determine the allocation of necessary data and a header orthe like is added.

[0400] As an example of this output data, the sequence c shown in FIG.65 is adopted, the decoding result of the picture which is subjected tothe rough quantization is obtained only by reading the first half of theGOP. In addition, since the data of the rough quantization residualdifference is small compared with finely quantized data, a moredata-efficient constitution can be obtained than storing the extractedrough quantization data before the fine quantization data.

[0401] Further, as another example, variable processing such as anarrangement of the sequence c shown in FIG. 70 may be performed. Thusconstituted, the ratio of the C component (component coded by performingthe rough quantization) out of the whole largely reduces so that anallowance can be made in the reading speed from the medium to enable askip search or the like. Further, as will be described later, when theonly the I picture and the P picture are arranged in summary, the deviceof the invention is operated so that only the data which is subjected tothe rough quantization of the I picture and the P pictures is decoded.

[0402] When the coding of the I picture is ended by allowing the Ipicture to pass through the subtracter 106, the B picture is coded withbidirectional prediction with the last P picture in the preceding GOP interms of time. An output of the preprocessor 101 is compared with thedata (arrows are omitted in FIG. 70) from the memory of the referenceframe so that the motion vector is detected and the prediction mode andthe frame structure are judged. On the basis of the result of judgment,the data in the reference frame memory in which the output of thepreprocessor 101 most favorably agrees with the data from the referenceframe memory is read as data in the forward direction portion and thebackward direction portion from the image memory 120 so that the datathus read and the output result of the preprocessor 101 of the B pictureare subtracted by the subtracter 106 (this result is referred to as timeresidual difference component for both P picture and B picture). Thedata. in the forward direction portion and in the backward directionportion is read from the picture memory 121 so that the data and theoutput of the preprocessor 101 is subtracted by the subtracter 107 fororthogonal transform entropy coding. The same process is performed withrespect to the P picture for coding the P picture.

[0403]FIG. 69 is a view showing an example of a statistical amount ofthe coded data, the view showing a distribution of the code amount atthe time when the number of frames in the GOP: N=15 and cycle of the Ipicture and the P picture: M=3. It is shown in FIG. 69 that the Ipicture and the P picture account for about 50% of the whole. When thehierarchy is divided with the resolution, the frequency, and thequantization at least with respect to this part or the I picture asdescribed above, the code amount which is to be played back furtherreduces so the travel time of the optical head can be shortened therebyfacilitating the realization of the functions such as the skip search orthe like.

[0404]FIG. 70 shows a processing sequence in the above-mentioned case.In FIG. 70, an arrangement of the I picture, P pictures and B picture ofthe original picture are coded so that the processing described inembodiments 12, 13 and 14 are performed only with respect to the Ipicture and the P pictures out of the aforementioned pictures while theB picture is coded without hierarchization. A sequence in which the Ipicture and the P picture are processed in accordance with theprocessing shown in embodiment 12 is referred to as sequence b while asequence in which the I picture and the P picture are processed inaccordance with the processing shown in embodiment 14 is referred to assequence c.

[0405] In each sequence, the data is constituted by fixing and arrangingin summary at the front of the GOP the I picture component and the Ppicture component of respective low resolution components (R), the lowfrequency components (L) and the rough quantization component (C) byrespective data reconstructor device 125. With the sequence a, the lowresolution picture of the I picture and the P picture can be decodedonly with the low resolution component (in the sequence a of FIG. 70,core area portion after the data reconstruction) of the I picture and Ppicture with the result that the device can easily cope with skipsearch. Naturally, the data in the area other than the core area is notrequired to be arranged as shown in FIG. 70. It goes without saying thatthe data may be arranged in an order of frame numbers at the time ofencoding.

[0406] With respect to the sequence b, the low frequency component ofthe I picture and the P picture can be formed only with the lowfrequency component (core area part after data reconstitution in thesequence b of FIG. 70) so that the device is capable of easily copingwith the skip search. With respect to the sequence c, rough quantizationpicture of the I picture and P picture can be decoded only with therough quantization component of the I picture and P picture (the corearea part after data reconstruction in the sequence c of FIG. 70) sothat the device can easily cope with the skip search. With respect tothe sequence c, rough-quantization picture of the I picture and Ppicture can be decoded only with the rough quantization component of theI picture and P picture (the core area part after data reconstruction inthe sequence c of FIG. 70) so that the device can easily cope with theskip search.

[0407] For example, in a structure shown in FIG. 63, a coding loopincluding the reprocessor 104 is not used for the B picture so that thedevice may be operated in such a manner that the data is coded only witha coding loop including the preprocessor 101. In a structure shown inFIG. 66, all frequency components may be coded with the firstvariable-length encoder 126. Further, in a structure shown in FIG. 68, afine quantization may be performed at the quantizer 110 for coding thedata.

[0408] Most ideally, the basic data such as low frequency side data maybe collected at the front of the GOP. It goes without saying that thedata may be shifted a little so that the data may be overlapped with thefront of the unit which constitutes an error correction code. Arrangingthe basic data corresponding to the unit of the error correction code inthis manner can be practiced in the same manner in other embodiments.

[0409] Embodiment 15

[0410] Embodiment 15 of the present invention will be explained withrespect to FIG. 71 and FIG. 72. FIG. 71 is a view showing thearrangement of DCT blocks and an example of an arrangement outline ofthe frequency component in bitstreams of one block. FIG. 71A shows thatone macroblock is formed of the header of the macroblock, the DCT blocksY1 to Y4 of a luminance signal, a DCT block U1 of a color differencesignal (B−Y) and a DCT block V1 of a color difference signal (R−Y) withrespect to the arrangement of the whole DCT block. FIG. 71B shows thatone low-frequency component of the macroblock is formed with themacroblock header, the DCT blocks Y1L to Y4L of a luminance signal, theDCT block U1L of the color difference signal (B−Y) and a DCT block V1Lof a color difference signal (R−Y) with respect to an arrangement of alow-frequency component DCT block.

[0411] Further, FIG. 71C shows that one high-frequency macroblock isformed with the DCT blocks Y1H to Y4H of a luminance signal, the DCTblock U1H of the color difference signal (B−Y) and the DCT block V1H ofthe color difference signal (R−Y) with respect to an arrangement of thehigh area component DCT block. FIG. 71D shows a concept of anarrangement of frequency component data in bitstreams of one block.FIGS. 72A and 72B are a block diagram showing a digital video signaldecoding processing unit, and a view showing an operation conceptthereof. In FIG. 72A, reference numeral 130 denotes a mode switcher as amode switching means, 131 a data rearranger as a data rearranging means,132 a decodable determiner, 133 a variable-length decoder and 134 aswitch. The decodable determiner 132 and the switch 134 constitute adata operating means. Reference numeral 135 denotes an inversequantizer, 136 an inverse DCT circuit, 137 an image memory, 138 anadder, and 139 an inverse scan converter.

[0412] Next, an operation will explained. The data shown in FIG. 71 is acode arrangement assembled in 8 bits (1 byte) for example, in thevertical direction. In each macroblock, information is described withrespect to the macroblock which is referred to as the macroblock header.This information refers to, for example, an increment address, aquantization scale code, a motion vector, a marker bit, a macroblockpattern or the like.

[0413] The coded data of each DCT block follows this macroblock header.A method for embedding this data is constituted so that a byte isconstituted with bitstreams to arrange each byte in order. Since eachDCT block has a variable code length, the block boundary and theboundary between the header and the data is not completed in the unit ofbytes. It often happens that the boundary exists in the midst of oneunit of byte. The data in each block has a variable length, and alower-frequency region is provided at a position nearer to the side ofthe macroblock head.

[0414] This data is divided into the a low frequency component (L) and ahigh-frequency component (H) to constitute a coded data as shown in FIG.71B and 71C by setting a fixed length code amount which is irrelevant tothe event as a maximum value (the event is a unit for providing onevariable-length code, and in the case of the DC component, the DCcomponent constitutes one event while in the case of the AC component acombination of non-zero DCT coefficient and the run length constitutesone event for performing run length coding. One event completes with acode referred to as EOB at the end of the block).

[0415] Next, an operation shown in FIG. 72 will be explained. In thebeginning, a mode signal is inputted from a microprocessor or the liketo the mode switcher 130, the signal indicating that the skip search isbeing performed, or the normal continuous playback being performed. Inthe meantime, the playback signal from the disc is amplified with anamplifier, and is digitally demodulated to perform an error correctionby performing a differentiation operation from an output data obtainedafter a signal playback is performed with a clock which is subjected tophase synchronization and is outputted from a PLL or the like, followedby separating an audio signal from a layer of a certain system whichconstitutes video signal data and audio signal data. Then the bitstreamof the video signal is extracted and is inputted to the data rearranger131.

[0416] The output (control signal) of the mode switcher 130 is suppliedto the data rearranger 131 and the decodable determiner 132. The datarearranger 131 obtains a control signal and reconnects the data beforedivision from an L component and an H component shown in FIG. 71, oroutputs only the L component to the variable-length decoder 133. Thevariable-length decoder 133 extracts a boundary of events in the Lcomponent region together with the decodable determiner 132. The portionup to the boundary is decoded and outputted to the switch 134. Thisswitch 134 is connected so that no zero is inserted at the time of thenormal playback. The switch 134, which is controlled with an output ofthe decodable determiner 132 inputs the decoded low-frequency componentto the DCT block. In the meantime, the whole DCT block is constituted sothat a zero is inserted into the high-frequency side of the DCT block.

[0417] At the time of decoding, the data of the DCT block constituted inthe aforementioned manner is subjected to the inverse DCT process. Then,the reading of the image memory 137 is controlled in accordance with thecases of respective pictures to be added by the adder 138. In the caseof the I picture, the output of the adder 138 is passed through. In thecase of the P picture, the P picture is corrected only by the motionvector of the I picture and P picture to be added. In the case of the Bpicture, the B picture is corrected by the motion vector from both the Ipicture and the B picture to be added.

[0418] Further, the DCT mode and the prediction mode motion vector atthis time are controlled on the basis of information obtained bydecoding the header code. In accordance with the aforementioned process,the data which is subjected to the motion compensation prediction isdecoded and is stored in the image memory 137. The picture is restoredto the original constitution order of the GOP. The inverse scanconverter 139 converts the buffering and the block scan into the rasterscan in the output order of the picture.

[0419] Embodiment 15 is represented to be fixed in length even when theembodiment is shorter than the skip of the macroblock or thepredetermined fixed length data. However, even when the length isshorter than the fixed length, the L component can be taken out withcertitude by detecting the EOB every time. Consequently, it goes withoutsaying that no problem is caused even when the L component data isconnected to the subsequent block. Further, the EOB may be attached tothe event demarcation as the L component data when the length exceedsthe predetermined length. Further, it goes without saying that aninformation adding means for adding additional information such as anaudio signal, a header or the like and a correction code is furtherprovided to be added to the data in the high-frequency region though notparticularly shown in the figures in the explanation of theaforementioned embodiments.

[0420] Embodiment 16

[0421] Next, embodiment 16 of the present invention will be explained byreferring to FIG. 73 and FIG. 74. FIGS. 73A and 73B are a block diagramof a digital video signal coding processing unit and a view showing anoperation concept thereof. In FIG. 73A, reference numeral 140 denote arate controller. Here, as encoding means, a first variable-lengthencoder 126 and a second variable-length encoder 127. Like parts orcorresponding parts are denoted by like numeral in FIG. 63.

[0422] Next, an operation will be explained. An interlace input picturedata is buffered with the preprocessor 101 to convert a raster scan intoa block scan. The I picture is decoded without performing a calculationbetween frames using an output of the frame memory which is subjected tothe intra-frame coding. Consequently, in the case of the I picture,nothing is inputted to the image memory 120 which is an input of thesubtracter 106 so that the video signal passes through the subtracter106.

[0423] This data is orthogonally converted into the frequency componentby the DCT circuit 108, and is converted from the low frequency regioninto the block scan to be subjected to an appropriate quantization bythe quantizer 110. A low-frequency region data up to the data of the DCTcoefficient at a specific position out of this quantized data is subjectto entropy coding and outputted to the data reconstructor 125 via thefirst variable-length encoder 126.

[0424] Further, the second variable-length encoder 127 performs thevariable-length coding of the DCT coefficient after the data locatedafter the aforementioned specific position. With respect to the codingof the motion vector and the DC component, only the firstvariable-length encoder 126 may be used at least. It is required thatthe EOB is added both to the L component and to the H component even inone block so that the boundary of the L component changes at rateswithout limitations of codes. The boundary of the L component can bechanged at a rate by temporarily arranging an EOB code at a demarcationpart of the L component and the H component.

[0425] In the meantime, the data quantized by the quantizer 110 issubjected to the inverse quantization by the inverse quantizer 114 to beinversely converted into a space component data by the inverse DCTcircuit 116.

[0426] The I picture is decoded without performing a calculation betweenframes using an output of a frame memory which is subjected to theintra-frame coding. Consequently, in the case of the I picture, sincenothing is inputted from the image memory 120 to the adder 118, the datais allowed to pass through the adder 118. The output of the adder 118 isused as data stored in the image memory 120. At least the I picture, orthe I picture data and the P picture data are required to be stored inthe image memory 120. That is because the I picture and the P picturedata are required for decoding the B picture normally in the MPEG 1 andthe MPEG 2 as reference data.

[0427] When the coding of the I picture is ended, the B picture is codedin the bidirectional prediction with the last P picture in the precedingGOP. Then, the output of the preprocessor 101 is compared with the data(arrows in the drawings omitted) from the reference frame memory todetect the motion vector and to judge the prediction mode and the framestructure. On the basis of the result of judgement, the data in thereference frame memory in which the output of the preprocessor 101 ismost suitable with the data from the reference frame memory in thereference frame memory is read from the image memory 120 together withthe data in the forward direction portion and in the backward directionportion. The data and the output result of the preprocessor 101 aresubtracted by the subtracter 106 (the result is referred to as timeresidual difference component with respect to the P picture and the Bpicture). This time residual difference component is subjected to DCTprocess, quantization and variable-length coding process.

[0428] When the data is divided into the low-frequency region and thehigh-frequency region, the rate becomes indefinite in the frequencycomponent. Consequently, since the data rate in the low-frequency regiondoes not become definite, the scope in which an actuator of the head canbe controlled cannot be completely compensated for. Here, the ratecontroller 140 renders the low-frequency component region variable. Therate controller 140 controls the rate so that a size of thelow-frequency region becomes variable with respect to the target rate asshown in FIG. 73B.

[0429] In other words, while monitoring the output of the firstvariable-length encoder 126, the rate controller 140 reduces the size ofthe area occupied by data in the low-frequency region when the monitoredoutput is larger than the target rate set by the application. When thecode amount of the first variable-length encoder 126 is small, the ratecontroller 140 enlarges the area of the low frequency region. In thismanner, while monitoring the code amount, the rate controller 140appropriately changes the setting of the occupied area in thelow-frequency region with respect to the first variable-length encoder126 and the second variable-length encoder 127.

[0430] Additionally, for example, a temporary coding may be performed todetermine the standard for setting of the occupied area of thelow-frequency region from the result as to which region has largernumber of codes and which region has smaller number of codes therebysetting the target rate.

[0431]FIG. 74 is a block diagram of a digital video signal decodingprocessing unit, a view showing the decoding processing for decodingdata coded as described above. In FIG. 74, reference numeral 141 denotesan EOB retrieval unit. Like parts or corresponding parts are denoted bylike numerals in FIG. 72A. A mode signal indicative of a state such thatthe data is being skip searched or the normal continuous playback isbeing operated is inputted from a microcomputer or the like to the modeswitcher 130. In the meantime, a playback signal from the disc isamplified by an amplifier so that the playback signal is differentiatedwith a clock which is subjected to PLL, for digital demodulation. Anaudio signal is separated from a system layer by conducting an errorcorrection to extract video bitstreams to be inputted to the datarearranger 131. The output of the mode switcher 130 as mode switchingmeans is supplied to the data rearranger 131 and the decodabledeterminer 132. The data rearranger 131 obtains this control signal tobe operated so as to connect the data before the division from the Lcomponent and H component shown in FIG. 71. Otherwise, only the Lcomponent is outputted to the variable-length decoder 133 which servesas a decoding means without being connected to the H component.

[0432] Theoretically, it never happens that the L component is severedin the midst of the events. In consideration of a case where the signalquality such as skip search or the like is not favorable, the boundaryof the events is confirmed with the variable-length decoder 133 and thedecodable determiner 132 so that the portion up to the boundary isdecoded and outputted to the switch 134. The switch 134 is operated insuch a manner that it is always turned on with respect to the playbackdata with a good signal quality like at the normal playback. Here, thedecodable determiner 132 and the switch 134 constitute a data operatingmeans.

[0433] The switch 134 is controlled with the decodable determiner 132 sothat a zero is inserted into the high-frequency side of the of the blockfrom the low-frequency component which has been successfully decodedthereby constituting the DCT block. Then, the data is subjected toinverse DCT so that the output of the adder 138 is passed through withrespect to the case of the I picture. In contrast, with respect to the Ppicture, the data is corrected and added by the portion of the motionvector in the I picture of the reference. With respect to the B picture,the reading of the image memory 137 is controlled and added by the adder138 so that the B picture is corrected by the portion of the motionvector from the I picture and the P picture to be added. The DCT mode,and the prediction mode motion vector are controlled by decoding a codeof the header. The data which is subjected to motion compensationprediction in this manner is decoded and is stored in the image memory137. Then, the picture is rearranged into the original constitutionorder. The inverse scan converter 139 buffers the data and converts thedata in the output order from the block scan to the raster scan.

[0434] Further, in the aforementioned explanation, an example isexplained in which a size of the DCT coefficient is controlled. Thenumber of events may be controlled instead. In this case, it sometimeshappens that the L component does not attain a predetermined number ofevents and EOB is added. However, since the EOB retrieval unit 141monitors the appearance of the EOB, the L component can be detected withcertitude. Here, in particular, the data is reconstituted on the basisof the data in the low-frequency region, the data in the high-frequencyregion, and the EOB respectively. That is, the data rearranger 131 andthe EOB retrieval unit 141 constitutes a data reconstructing means.

[0435] Since the energy after the DCT is naturally small, it goeswithout saying that the L component and the H component are desirablycoded in the same manner with respect to the non-coded block which ishot coded. With respect to the H component, the data excluding the Lcomponent is ideally run-length coded. BY setting the L component to 0,the H component may be coded. Since it is possible to cope with thestructure same as the variable-length decoder of the normal MPEG, thisone can be simplified in terms of circuits.

[0436] Embodiment 17

[0437] Embodiment 17 of the present invention will be explained on thebasis of FIG. 75. FIG. 75 is a block diagram showing a digital videosignal decoding processing unit. In FIG. 75, reference numeral 142denotes a multiplexer, 143 a switch, 144 a first variable-lengthdecoder, 145 a second variable-length decoder, 146 a first inversequantizer, 147 a second inverse quantizer, 148 and 149 adders, 150 and151 image memories, and 152 resolution inverse converter. FIG. 75 alsoshows a low resolution decoding unit as decoding means. Like parts orcorresponding parts are denoted by like numerals in FIG. 72A and anexplanation thereof is omitted.

[0438] Next, an operation of embodiment 17 will be explained. What isshown in FIG. 75 may be considered as corresponding to the processingblock of the video data of a playback signal from the disc in the casewhere the coded data as described in FIG. 68 is recorded on an opticaldisc or the like. A mode signal indicative of a state such that a skipsearch is being performed or normal continuous playback is beingperformed is inputted from a microcomputer or the like to the modeswitcher 130 as a mode switching means. In the meantime, the playbacksignal from the disc is amplified at the amplifier and a playback signalis differentiated with a clock subjected to PLL for digitaldemodulation. Then an audio signal is separated from the system layer toextract video bitstreams.

[0439] This extracted video bitstream is inputted to the multiplexer142. The multiplexer 142 sends the data of the low resolution componentto the second variable-length decoder 145 while sending the other datato the first variable-length decoder 144 via the switch 143.

[0440] The switch 143 is controlled by the mode switcher 130. As a mode,although only the output of the playback picture of the low resolutioncomponent is demanded at the skip search or the like, the switch 143 isoperated to suspend the sending of redundant data in the case where theresolution residual difference component is played back halfways.Further, at the time of the normal playback, the switch 143 remainsconnected.

[0441] The second variable-length decoder 145 decodes a Huffman code andthe run length code to be inversely quantized by the second inversequantizer 147 and is converted from a frequency component into a spacecomponent by the inverse DCT circuit 136.

[0442] With respect to the I picture, the converted data is passedthrough the adder 149 to be stored in the image memory. In the case ofthe P picture, the first frame of the P picture is read from the Ipicture stored in the image memory and the P picture of the second frameor after is referred to the preceding P picture stored in the imagememory and corrected by the motion vector portion to be subjected to themotion compensation prediction by the adder 149. In the case of the Bpicture, the same operation is performed on the basis of the I pictureand the P picture.

[0443] In FIG. 75, a motion vector, a quantization parameter for inversequantization and a prediction mode are outputted from thevariable-length decoder. Such a motion vector, a quantization parameterand the a prediction mode are the same as shown in FIG. 74. A loop shownby a dot line block in FIG. 75 is a constitution unit for decoding a lowresolution component. Since the decoding result is interpolated betweenpixels by the resolution inverse converter 152 as interpolation videogenerating means to compensate for the decoding result as resolutionresidual difference component, the decoding result is inputted to theimage memory 150.

[0444] The decoding of the resolution residual component at the time ofthe normal playback is outputted as a picture by the inverse scanconverter 139 in combination with the decoding result of the lowresolution component (or in accordance with the division processing inthe case where the decoding of the resolution residual component isperformed by time division). The data can be decoded into the frequencycomponent by the first variable-length decoder 144 via the switch 143.The first inverse quantizer 146 inversely quantizes the data and theinverse DCT circuit 136 decodes data into the resolution residualdifference component data in the space region.

[0445] The image memory 150 refers to the pixel interpolation data ofthe low resolution component, and further the P picture refers to the Ipicture, the B picture refers to the I picture and the P picture so thatthe data is corrected in position by the motion vector portion with theresult that the data is read from the image memory 150, and the motioncompensation prediction is decoded by the adder 148.

[0446] Further, in the case of the skip search, to prevent theresolution residual difference component from being played backhalfways, superfluous data is prevented by the switch 143 from beingoutputted from the inverse DCT circuit 136, by suspending the output ofthe resolution residual difference. Consequently, only the pixelinterpolated data of the low resolution component is outputted (theoperation will be the same even if a switch is provided on the inputpart of the image memory 150) via the image memory 150 and via theinverse scan converter 139.

[0447] Embodiment 18

[0448] Embodiment 18 will be explained with respect to FIG. 76 and FIG.77. FIG. 76 is a block diagram showing a GOP address generating unit anda disc control unit, the diagram showing, in particular, a processingblock in the case of recording the aforementioned rate information on asequence header. In FIG. 76, reference numeral 153 denotes a register,154 a GOP address calculator, and 155 an optical head/disc rotationcontrol converter as a head position converting means and as a discrotation control converting means. Further, FIG. 77 is a block diagramshowing a GOP address generating unit and a disc control unit includinga playback processing, the diagram showing, in particular, a structurefor performing a GOP playback from a disc on which the aforementionedrate information is collected at several places. Referring to FIG. 77,reference numeral 156 denote a playback amplifier, 157 a digitaldemodulator, 158 an error corrector, 159 a system layer processor, and160 a rate data memory. The system layer processor 159 and the rate datamemory 160 constitute a data rate information extracting means.Reference numeral 161 denotes a GOP number counter. The GOP addresscalculator 154 and the GOP number counter 161 constitute a positioninformation calculating means.

[0449] Next, an operation of embodiment 18 will be explained. An overallrate of one program can be optimized by rendering the rate per one GOPvariable as described in the conventional example with the result thatthe quality of the picture can be considerably improved. However, it isnot apparent that the data falls on the front of the GOP until watchingthe data content. Also, in the case where it is desired that thesoftware which has been matched halfway be played back again from thatposition, only way is to detect the starting position by retrieving thedata on the disc minutely.

[0450] Here, in such a case, the rate control of the variable rate isset, in the beginning, to discrete rate goals such as 1 Mbits, 1.5Mbits, 2 Mbits, 2.5 Mbits, 3 Mbits or the like so that each of the rateinformation in all the GOP is recorded on a disc. In particular, itwould be most effective when the rate information with respect to eachGOP is recorded on a TOC (Table of Content: a record region is assignedto the very beginning of the disc so that information such as the title,the recording time or the like is recorded), a semi-TOC or the like.

[0451] Further, the rate information with respect to GOP may beassembled in the sequence header of video bitstreams. For example, twohour software 14.4 k pieces of GOP. The rate information at this timemay be represented with 3 bits when the rate information can be dividedinto five kinds of rates. Consequently, all the GOP rates can berecorded on the disc with 5.4 k (14.4 k pieces×3 bits/8 bits/bytes).

[0452] A high speed access can be made to a desired GOP by storing therate information of each of the GOP in the rate data memory 160 shown inFIG. 77 and adding up the information length corresponding to the value.

[0453] The device will be explained with respect to FIG. 76. The Huffmancode, the run length code are decoded and the header is deciphered sothat the motion vector and the kind of picture are judged.

[0454] In the meantime, the sequence header is decoded so that the rateinformation is inputted to the GOP address calculator 154. In addition,the address information of the GOP which is currently accessed to isstored in the register 153 so that the GOP front address for the nextaccessed is calculated and stored in the register 153. At the same time,by using the optical head/disc rotation control converter 155 up to thefront of the next GOP to be accessed, the position of the optical headis determined on the basis of the address. Then a control signal to thenext access is calculated from a difference between the GOP which isbeing accessed and the front address to be accessed. Based on thiscontrol signal, the position control of the optical head actuator andthe control of the disc rotation will be performed.

[0455] The playback processing will be explained by referring to FIG.77. The optical head and the optical head rotation are controlled so asto read the data either directly or indirectly from the TOC region or.the region corresponding to the TOG region (after the rate informationdescription address is designated, this address portion is accessed toread the rate information). Then, the playback signal from the opticalhead is amplified with a playback amplifier 156 to detect the wave ofthis signal by the digital demodulator 157 to differentiate the signalinto the digital signal for digital demodulation.

[0456] The playback signal which is digitally demodulated into a digitalsignal is inputted into the error corrector 158 to correct an errorincluded in the playback signal. The data after the error correction isseparated into the audio bitstreams, video bitstreams and other dataitems by the system layer processor 159.

[0457] For example, it is judged which kind of data (AV (video andaudio) data, text data and binary data such as program or the like) thissignal belongs to cut and classify the stream channel. In such aprocess, the aforementioned rate information is stored in the rate datamemory 160.

[0458] In contrast, information as to which number of GOP is desired tobe processed is generated by using the GOP number counter 161. On thebasis of the address calculated by the GOP address calculator 154 theoptical head actuator and the disc rotation speed of the disc arecontrolled.

[0459] In the aforementioned explanation, an example is given in whichthe GOP number counter 161 receives a signal from the system layerprocessor 159. In the case where a part which the user I/F such as themicrocomputer substitutes a processing or in the case where theoperation moves from the playback to the skip search, it would be moreefficient to input address data from a variable-length decoder or thelike for processing the video bitstream.

[0460] Embodiment 19

[0461] Next, embodiment 19 of the present invention will be explainedbased on FIG. 78, FIG. 79 and FIG. 80. An operation will be explainedhereinbelow. FIG. 78 is a view showing a signal processing unit in thecase in which the division by the frequency of the digital signalplayback unit and the division by the quantization are performed, theview being a block diagram of a structure used in the playbackprocessing in the case where the rate information is collected andrecorded at several places on the disc. Like parts or correspondingparts are denoted by like symbols in the aforementioned embodiments inthe drawings.

[0462] The optical head or the optical head rotation are controlled sothat the data is either directly or indirectly read from the TOC regionor the region corresponding to the TOC region (the rate informationdescription address is designated). The playback signal is amplifiedwith the playback amplifier 156. Then, this signal is detected by thedigital demodulator 157 to be differentiated for digital demodulation.Consequently, the playback signal which becomes a digital data isinputted to the error corrector 158 to correct an error included in theplayback signal. The data free from errors is separated into audiobitstreams and video bitstreams by the system layer processor 159 andother data is processed as well.

[0463] For example, it is judged which kind of data (AV) data, textdata, or binary data or the like such as programs) this signal belongsto divide and classify stream channels. Out of them, the aforementionedrate information is stored in the rate data memory 160. In contrast,information is generated as to which number of the GOP is desired to beprocessed is generated by using the GOP number counter 161. Then theaddress is calculated by the GOP address calculator 154. On the basis ofthe address calculated by the GOP address calculator 154, the opticalhead actuator and the rotation speed of the disc are controlled.

[0464] In this manner, at the time of skip playback, skipping isperformed on the disc to find the address of the GOP to be accessed.then the skipping is performed to make an access to a desired GOP,low-frequency region data obtained by using a structure described, forexample, in embodiment 16 is played back and described on the screenwhile calculating the next address in the same manner.

[0465] A mode signal indicative of the state such that the data is beingskip searched or a normal playback is being continuously performed isinputted from a microcomputer to the mode switcher 130. As describedabove, the video bitstream is extracted to be inputted into the datarearranger 131. The output of the mode switcher 130 is supplied to thedata rearranger 131 and the decodable determiner 132. The datarearranger 131 obtains such a control signal to operate so that the databefore division is reconnected from the L component and the H componentin FIG. 71. Otherwise, the data rearranger 131 outputs only the Lcomponent to the variable-length decoder 133 without connecting the Lcomponent to the H component.

[0466] In embodiment 19, theoretically it does not happen that the Lcomponent is cut in the midst of the event. However, considering thecase where a signal having an unfavorable signal quality of the skipsearch or the like is decoded, the boundary of the event is confirmedwith the variable-length decoder 133 and the decodable determiner 132for assurance so that a portion up to the boundary is decoded andoutputted to the switch 134.

[0467] The switch 134 is controlled with an output from the decodabledeterminer 132 so that a zero is inputted to the high-frequency side ofthe block from the low-frequency component which has been successfullydecoded to constitute the DCT block. Then the reading of the imagememory 137 is controlled and added by the adder 138 so that the data issubjected to the inverse DCT in such a manner that the output of theadder 138 is passed through in the case of the I picture and the data iscorrected by the motion vector portion to be added in the case of the Ppicture and the data is corrected by the motion vector portion from theI picture and the P picture and is added in the case of the P picture.

[0468] Further, the DCT mode and the prediction mode motion vector atthis time are controlled by decoding the header code. In this manner,the data subjected to the motion compensation prediction is decoded andstored in the image memory 137 to constitute the picture in the originalconstitution order. At the inverse scan converter 139, the data isbuffered to convert the data from the block scan to the raster scan inthe output order of pictures. In addition, the switch 134 is notconnected so that a zero is inserted at the time of the normal playback,but is controlled to operate and play back only the playback data.

[0469] Further, in the case where the data is divided and coded into thelow frequency region and the high frequency region, there may be casesin which a quantization table which places an emphasis on the lowfrequency side, a quantization table which places an emphasis on thehigh frequency side, and a fine quantization irrespective of thefrequency region quite evenly with respect to one quantization table areprepared. Such a case can be realized when two sets of thevariable-length decoder and the inverse quantizer are provided as can beseen in the local decoder shown in FIG. 68. At that time, the datarearranger 131 has to be a multiplexer.

[0470] Next, an operation of embodiment 19 will be explained on thebasis of FIG. 79. FIG. 79 is a view showing a signal processing unit inthe case where division by the bit length of the digital signal playbackunit is performed, the view being a block diagram for explaining anembodiment with respect to the playback processing in the case where theaforementioned rate information is collected and recorded particularlyat several places on the disc. For example, at the very beginning of theplayback of the disc which is a predetermined region on the recordingmedium, the optical head and the optical head rotation is controlled sothat data is directly or indirectly read from the TOC region or a regioncorresponding to the TOC region (designating the rate informationdescription address), and the playback signal from the optical head isamplified with the playback amplifier 156 so that this signal isdetected with the digital demodulator 157 to be differentiated into adigital signal for digital demodulation.

[0471] As a consequence, the playback signal which has become a digitaldata is inputted to the error corrector 158 to correct an error includedin the playback signal. The data free from errors is separated intoaudio bitstreams and video bitstreams and other data items are processedas well.

[0472] For example, this signal judges whether the data is video audiodata, text data or binary data of programs or the like to cut andclassify the stream channel. Out of such data, the aforementioned rateinformation is stored in the rate data memory 160. In the meantime,information is generated by the GOP number counter 161 as to whichnumber of the GOP is desired to be processed, and the address iscalculated by the GOP address calculator 154 to control the actuator andthe rotation speed of the disc.

[0473] In this-manner, the address of the GOP to be accessed at the timeof the skip playback is searched for by skipping on the disc. When thedesired GOP is accessed, the next address is calculated in the samemanner and at the same time the data of the low frequency regionobtained by using the structure described, for example, in embodiment 15is played back to represent the data in one screen.

[0474] A mode signal indicative of the state such that the skip searchis being performed or a normal continuous playback is being performed isinputted to the mode switcher 130 from the microcomputer or the like.The video bitstream is extracted and is inputted to the data rearranger131. An output of the mode switcher 130 is supplied to the datarearranger 131 and the decodable determiner 132. The data rearranger 131obtains this control signal to operated to reconnect data before thedivision from the L component and the H component of FIG. 71. Otherwise,the data rearrarger 131 outputs only the L component to thevariable-length decoder 133 without connecting the L component to the Hcomponent.

[0475] The variable-length decoder 133 and the decodable determiner 132extract the boundary of the events in the L component so that theportion up to the boundary is decoded and outputted to the switch 134.The switch 134 is controlled by the output of the decodable determiner132 so that a zero is inserted to the high-frequency side of the blockfrom the low-frequency component which has been successfully decoded toconstitute a DCT block. The data is subjected to the inverse DCT. In thecase of the I picture, an output of the adder 138 is passed through. Inthe case of the P picture, the picture is corrected by the motion vectorportion within the I picture of the reference to be added. The readingof the image memory 137 is controlled and added by the adder 138 so thatthe data is corrected by the motion vector portion.

[0476] Further, the DCT mode and the prediction mode motion vector arecontrolled by decoding the header code. In this manner, the datasubjected to the motion vector prediction is decoded and stored in theimage memory 137 to constitute the picture in the original order of theconstitution of the GOP. The inverse scan converter 139 buffers the datato convert the data from the block scan to the raster scan. Further, theswitch 134 is not connected to insert a zero at the time of the normalplayback to perform connecting operation to play back only the playbackdata.

[0477] Next, an operation of FIG. 80 will be explained. FIG. 80 is aview showing a signal processing block in the case where the data isdivided with the resolution of the digital signal playback part, theview being a block diagram explaining an embodiment with respect to theplayback processing in the case, in particular, where the aforementionedrate information is collected at several places on the disc. The opticalhead and the rotation of the optical head is controlled so that the datais directly or indirectly (rate information description addressdesignated) read from the TOC region or a region corresponding to theTOC region at the beginning of the disc playback, and the playbacksignal from the optical head is amplified by the playback amplifier 156.This signal is detected with a digital demodulator 157 to bedifferentiated into the digital signal for digital demodulation.

[0478] Consequently, the playback signal which has become digital datais inputted to the error corrector 158 in which an error included in theplayback signal is corrected. The data free from errors is separatedinto audio bitstreams and video bitstreams by the system layer processor159, and other data items are processed as well. For example, by judgingwhether the signal is video audio data, text data or binary data ofprograms or the like, the stream channel is cut and classified. Out ofsuch data, the aforementioned rate information is stored in the ratedata memory 160.

[0479] In the meantime, information is generated by the GOP numbercounter 161 as to which number of the GOP is desired to be processed,and the address is calculated by the GOP address calculator 154 tocontrol the optical head actuator and the rotation speed of the disc. Inthis manner, the address of the GOP to be accessed at the time of theskip playback is searched for by skipping on the disc. When the desiredGOP is accessed, the next address is calculated in the same manner andat the same time the data of the low frequency region obtained by usingthe structure described, for example, in embodiment 15 is played back torepresent the data in one screen.

[0480] A mode signal indicative of the state such that the skip searchis being performed or a normal continuous playback is being performed isinputted to the mode switcher 130 from a microcomputer or the like. Thevideo bitstream is extracted and inputted to the multiplexer 142. Themultiplexer 142 sends the low resolution component data to the secondvariable-length decoder 145 while sending other data items to the firstvariable-length decoder 144 via the switch 143. The switch 143 iscontrolled with the mode switcher 130. Despite that only the playbackpicture output of the low resolution component is demanded as a mode inskip search or the like, the switch 143 is operated so as to be turnedoff in the case where the resolution residual component is played backhalfways. Further, when a playback operation is performed in which agood signal transmission quality is attained in such cases as the normalplayback, the switch 143 is turned on.

[0481] The second variable-length decoder 145 decodes a Huffman code anda run-length code. The data is subjected to inverse quantization by thesecond inverse quantizer 147 to be converted from a frequency region tothe space region by the inverse DCT circuit 136. When the data is the Ipicture, the data passes through the adder 149 to be stored in the imagememory. When the data is the P picture, the P picture is referred tofrom the image memory followed by being corrected in position by themotion vector portion to be read to decode the motion compensationprediction by the adder 149. When the data is the B picture, the sameoperation is performed with respect to the I picture and the P picture.

[0482] In FIG. 80, the motion vector, the quantization parameter for theinverse quantization, and the prediction mode are outputted from thevariable length decoder. Since the flow of information is the same asFIG. 74, an explanation thereof is omitted. A loop on the low side ofFIG. 75 is the decoding of the low resolution component. The decodingresult is subjected to pixel interpolation by the resolution inverseconverter 152 to compensate for the decoding result as the resolutionresidual difference, the data is inputted to the image memory 150.

[0483] Embodiment 20

[0484] Next, embodiment 20 of the present invention will be explainedwith reference to FIG. 81, FIG. 82 and FIG. 83. FIG. 81 is a blockdiagram for coding process. FIG. 82 is a block diagram for decodingprocess. In FIGS. 81 and 82, reference numeral 162 denotes a videosignal encoder as encoding means. 163 an audio signal encoder, 164 and167 memories, 165 and 168 memory controllers. The memory 164 and thememory controller 168 constitute a data supplying means. Further, thevideo signal encoder 162 and the memory controller 165 constitute a codeamount comparing means. Reference numeral 166 denotes a system layerbitstream generator. Reference numeral 169 denotes a variable-lengthdecoder and 170 a decoded signal processor after the variable-lengthdecoder. The variable-length decoder 169 and the decoded signalprocessor 170 serve as a data decoding means. The data rearranger 131 ofFIG. 82 serves as a data reconstructing means.

[0485] In the beginning, an operation of a structure shown in FIG. 81will be explained. Between the video signal encoder 162 and the systembitstream generator 166, the memory 164 is arranged. After the data isembedded between each of the GOPs of coded video signals, each of theGOPs is inputted to the system layer bitstream generator 166 while theaudio signal is coded with the audio signal encoder 163 followed bybeing inputted to the system bitstream generator 166 along with a videosignal to be subjected to an operation of adding headers or the like.

[0486] Here, data embedding operation in the memory 164 will bedescribed. The memory controller 165 serves as a control circuit of thememory 164 to control the coded video signal controls video signal dataso as to embed the space between each of the GOPs. A signal processingwill be explained by referring to FIG. 83 hereinbelow. FIG. 83 is a viewillustrating a concept of processing at the digital video signal recordand playback device. For example, in the case where (n+1)GOP endhalfways with respect to an access position of an optical head or acontrol unit of an error correction to generate a space of a data regionwhen nGOP generates superfluous data with respect to the access positionof the optical head and the control unit of an error control, the deviceof the invention is controlled so that, as shown in FIG. 83A, thesuperfluous nGOP data is embedded in a space part after (n+1)GOP, and inthe same manner a little amount of residual data of (n+1)GOP whichcannot be embedded in the space because nGOP is embedded and (n+2)GOPare embedded in a space part of (n+3)GOP (the data is embedded in adirection from the left to the right on the paper).

[0487] Further, as another method of control, the superfluous data isnot sent in the backward direction as described above. As shown in FIG.83B, when (n+2)GOP exceeds the access position a little so that the(n+3)GOP ends halfways with respect to the access position of theoptical head and the control unit of the error control, the device ofthe present invention is controlled so that the superfluous (n+3)GOPdata is embedded in the space part after the (n+2)GOP data, and in thesame manner, the residual data of (n+2)GOP which cannot be embeddedbecause (n+3)GOP is embedded is embedded in the space part of (n+1)GOPand (n+1)GOP which cannot be embedded is embedded in the space part ofnGOP (in the embedding direction from the right to the left on thepaper).

[0488] Next, an operation of a structure shown in FIG. 82 will beexplained. The memory 167 is controlled by the memory controller 168 sothat the data rearranged in accordance with the rule described withrespect to the aforementioned FIGS. 83A and 83B is restored to theoriginal state. For example, in the case where the data shown in FIG.83A is restored, the device of the invention is operated so that the GOPdata is restored to the original state such that nGOP portion whichfollows (n+1)GOP is connected to a part after nGOP data on the left sideof the paper followed by connecting (n+1)GOP data thereafter and thenconnecting (n+1)GOP data following the (n+2)GOP data.

[0489] This rearranging rule is required to be defined in advance as aformatting rule of a medium so that the rule is recorded as flaginformation in a well-organized region following, for example, the TOCregion. In the case where the rule is not defined, the rule must beclearly described somewhere on the medium.

[0490] Embodiment 21

[0491] Next, embodiment 21 will be explained by referring to FIG. 84,FIG. 85 and FIG. 86. FIG. 84 is a block diagram representing a signalprocessing unit in the case where the division by the frequency at thedigital signal playback part is performed, or the division by thequantization is performed. FIG. 85 is a block diagram representing asignal processing unit in the case where the division by the bit lengthat the digital signal playback part is performed, or the division by thequantization is performed. FIG. 86 is a block diagram representing asignal processing unit in the case where the division by the resolutionat the digital signal playback unit is performed, or the division by thequantization is performed. In FIGS. 84, 85 and 86, reference numeral 171denotes an IP selection indicator, 172 a decodable determiner and 173 aswitch. In FIG. 86, corresponding parts are shown as an example of thefirst decoding means, the second decoding means and the third decodingmeans. Like parts or corresponding parts in FIGS. 84, 85 and 86 aredenoted by like numerals, and an explanation thereof will be omitted.

[0492] Next, an operation of embodiment 21 will be explained. In FIGS.84 and 85, an optical head or the rotation of the optical head arecontrolled so that the data is read directly or indirectly (the rateinformation described address being designated) from a TOC region or aregion corresponding to the TOC region. A playback signal from theoptical head is amplified by the playback amplifier 156. This signal isdetected by the digital demodulator 157 to be differentiated into adigital signal for digital demodulation. Consequently, the playbacksignal which has become digital data is inputted to the error corrector158 to correct an error included in the playback signal. The data freefrom errors is separated into audio bitstreams, and video bitstreams bythe system layer processor 159 and other data items are processed aswell. In FIGS. 84, 85 and 86, a control signal is inputted into the IPselection indicator 171 from the mode switcher 130 as a mode switchingmeans for switching the decoding means on the basis of the specialplayback speed. Embodiment 21 is controlled so that the embodiment 21 isswitched over between a mode of displaying only the I picture or a modeof displaying the I picture and the P picture with this control signaland the skip search speed.

[0493] When skip search speed is 100 times, the GOP must be outputtedwith a considerable thinning if both the I picture and the P picture areoutputted on the screen. Consequently, the picture seems quite unnaturalwith respect to the movement of the played back screen. In such a case,to remove the unnaturalness, the mode is required to be switched to amode of playing back only the I picture. The decodable determiner 132(172 in FIG. 86) is designated to suspend the decoding of not only the Bpicture but also the P picture (the switch 173 serves for this functionin FIG. 86). At the same time, the image memory 137 (150 and 151 in FIG.86) is controlled to display only the I picture.

[0494] The screen display of the I picture and the P picture is normallyfavorable up to a speed of 15 times speed, but the screen display ofonly the I picture is more favorable at a speed of 15 times speed ormore. That is because when the whole I picture and the whole P pictureare displayed at a speed of 15 times speed, the continuity of the motionis extremely deteriorated since the GOP which can be played back in thesubsequent process is located at a place of the 5th GOP from the GOPcurrently displayed even if the screen is renewed for each frame.Further, when number of frames in the GOP is N=15 and the I picture andthe P picture has a cycle of M=3, the all the P pictures are decoded butonly the I picture and the second frame of the P picture (third and theninth frame in the GOP) are outputted, much finer skip search can beperformed.

[0495] As described above, the data state is divided and recorded bydividing the data state on the basis of the predetermined condition ofthe following cases such as a case where the data is recorded bydividing the frequency region to a predetermined position of each GOPread from the recording medium for recording data, a case where the datais recorded by dividing the data by the resolution, and a case in whichthe data is divided by the quantization level to be recorded. Then whenthe first data which is the basic data in the playback data and thesecond data excluding the basic first data is played back from datacollectively arranged, a decoding means is provided to obtain one of theplayback pictures out of the following cases; a case in which all thefirst and the second data is decoded, and a case in which a playbackpicture is obtained which corresponds to the low-frequency region of theI picture and P picture or the number of thinned pixels. Then, thedecoding means to be used at the time of the special playback may beswitched on the basis of the special playback speed.

[0496] It goes without saying that the setting of the way of displayingthe I picture and the P picture may be changed at the time of theplayback in the positive direction and at the time of the playback inthe negative direction. Since the P picture can be decoded only in thepositive direction of time, it is necessary to store screens which existbefore the P picture to be decoded at the time of the reverse directionplayback. Consequently, it is necessary to use superfluous memory forthat portion. To facilitate the reverse direction playback without usingsuch superfluous memory, the I picture and the P picture may be playedback at the time of the skip search in the positive direction and onlythe I picture is played back at the time of the reverse direction skipsearch.

[0497] Embodiment 22

[0498] Embodiment 22 will be explained on the basis of FIGS. 87, 88, 89and 90. FIG. 87 is a block diagram showing a signal processing unit inthe case where the division by the frequency at the digital signalplayback part is performed, or the division by the quantization isperformed. FIG. 88 is a block diagram showing a signal processing unitin the case where the division by the bit length at the digital signalplayback unit is performed. FIG. 89 is a view explaining a concept ofprocessing at the time of the skip search. In FIGS. 87 and 88, referencenumeral 174 denotes a field display controller. A system layer processor159 serves as a video data extracting means. Further, FIGS. 87 and 88shows corresponding parts as one example of video data decoding andplayback means. Reference numeral 130 denotes a mode switcher as a modeswitching means. Like parts or corresponding parts are denoted by likenumerals in the aforementioned embodiments in the drawings.

[0499] Next, an operation of embodiment 22 will be explained. In FIGS.87 and 88, an optical head and the rotation of the optical disc arecontrolled so that the data is directly or indirectly (the rateinformation described address being designated) read from a TOC regionor a region corresponding to the TOC region. A playback signal from theoptical head is amplified by the playback amplifier 156. This signal isdetected by a digital demodulator 157 to be differentiated into adigital signal for digital demodulating. Consequently, the playbacksignal which has become digital data is inputted to the error corrector158 to correct an error included in the playback signal. The data freefrom errors is separated into audio bitstreams, and video bitstreams bythe system layer processor 159 and other data items are processed aswell.

[0500] When, for example, the I picture and the P picture arecontinuously outputted to the screen at the time of the skip search, thescreen is outputted in the order denoted by arrows shown in FIG. 89. Atthis time, the even-field of the I picture and the odd-field of the Ppicture are continuous at the time of the skip search whereas there arefour vacant fields between them in the encode data. In other words, theplayback speed in encode data is five times as fast as the playbackspeed in the space between the odd-field and the even-field of the Ipicture. Therefore, the motion of the I picture varies in an unnaturalmanner due to the change in the playback speed from one time speed tofive times speed for each field.

[0501] This is replaced on the-same screen as the odd field or the evenfield of the I picture. Otherwise, a screen is prepared by embedding theaverage of the upper and lower scan lines in consideration of theinterlace for output. The image memory 137 shown in FIGS. 87 and 88 iscontrolled by using the field display controller 174 so as to constitutethe same screen in the subsequent P picture. Consequently, a skip amountbetween fields which is a space between fields coded at the time ofrecording data on each field of the picture which is played back can beuniformly obtained with the result that the jerkiness (unnatural motion)becomes inconspicuous.

[0502] Further, FIG. 90 is a view explaining a concept of processing atthe time of the reverse playback, a view particularly showing a fieldorder at the time of the reverse playback. Hereinafter, a field order atthe time of the reverse playback will be explained on the basis of FIG.90. At the time of the reverse playback, the reverse playback isperformed in the unit of frame constituting a pair of the odd field andthe even field. Specifically, when the operation moves from the oddnumber field to the even number field, the playback is performed in thesame direction as time on the image (a playback operation in which theprocess a is traced in FIG. 90). When the operation moves from the evennumber field to the odd number field, the two field portion is reverselysent in a direction reverse to time on the image (a skip operation inwhich the process b is traced in FIG. 90A).

[0503] However, when the aforementioned playback process is taken, athree times speed playback is provided with the result that a playbackpicture is provided which moves in an awkward manner to see so that theorder of motion can not be felt smoothly. When the image memory 137 iscontrolled by the field display controller 174 in FIGS. 87 and 88 sothat the playback picture is displayed in the reverse direction onescreen after another in the unit of field in the order of odd number,even number, odd number and even number as shown in FIG. 90B. Then sincethe skip amount between the fields can be almost uniformly obtained, thejerkiness becomes inconspicuous. However, with respect to thesynchronous signal at this time, a normal odd number and even numberfield relation is required to be maintained without inverting the fieldsynchronization signal.

[0504] The image memory 137 does not receive the output of the adder 138as it is to take a display method independent for each of the fields,but the output of the adder 138 is received independently from the imagememory 137. To perform such an operation, the order may be changed byproviding a buffer as a separate device. A memory may be used which hasthree ports in which an address control may be set independently. Theaforementioned operation can be realized even when the data ismultiplexed with a memory which can be operated at a very fast operationspeed to read the data. Further, since the inverse scan converter 139provides at least a memory of at least one field plus one splice, itgoes without saying that such buffering function may be incorporated inthe inverse scan converter 139.

[0505] Further, with respect to the slow playback out of the specialplayback, the jerkiness becomes conspicuous when the same frame isoutputted repetitively. Consequently, the frame is reconstituted andoutputted so that the playback interval becomes equal. For example, inthe case of the slow playback at ⅓ times speed, it does not happen that,for example, after decoded I frame is outputted three times, the decodedB frame is outputted three times. Instead, the first one frame isconstituted of an odd number field of the I frame. On the even numberfield side, the average of the upper and the lower lines may be taken.

[0506] In such a constitution, no picture shift appears in the verticaldirection of the screen due to line shifts in the interlaced picture sothat a stable picture can be obtained. The subsequent one frame outputsthe original I frame, and the subsequent one frame constitutes one framewith the odd number field of the I frame (on the even number field side,the average of the upper and lower lines may be taken). Then thesubsequent one-frame outputs the original B frame, and the subsequentone frame constitutes one frame with an even number field of the B frame(on the odd number field side the average of the upper and lower linesmay be taken). Consequently, a slow playback can be realized at an equalinterval in terms of time.

[0507] As this invention may be embodied in several forms withoutdeparting from the spirit of essential characteristics thereof, thepresent embodiments are therefore illustrative and not restrictive sincethe scope of the invention is defined by the appended claims rather thanby the description preceding them, and all changes that fall within themetes and bounds of the claims, or equivalence of such metes and boundsthereof are therefore intended to be embraced by the claims.

What is claimed is:
 1. A digital video signal record and playback devicefor recording and playing back on a recording medium a digital videosignal coded by using a motion compensation prediction and an orthogonaltransform, said device comprising: means for dividing one frame portionof video data into n areas (n>1) with respect to at least an I picturefor an intraframe coding at the time of recording; means for recordingan area which comes to the center on the screen in an area unit bygiving a priority to the area with respect to the I picture frame whichis divided into n areas while at the same time recording positioninformation representative of the recording position on the recordingmedium of divided 1 through n areas; means for reading only an arealocated at the center of the I picture from the recording medium at thetime of the special playback; a buffer memory for storing data in thearea which is read; and means for outputting only data in the centralarea which is read.
 2. A digital video signal record and playback deviceaccording to claim 1 wherein the data in the central area which is readat the time of the special playback is extended to one screen and isoutputted for performing the special playback.
 3. A digital video signalplayback device for playing back from a recording medium a digital videosignal coded by using a motion compensation prediction and an orthogonaltransform, said device comprising: means for reading at the time ofspecial playback only an area located at the center of an I picture fromthe recording medium wherein, after dividing one frame portion of videodata into n areas (n>1) with respect to at least the I picture for anintra-frame coding, an area which comes to the center on the screen isrecorded in an area unit by giving a priority to the area with respectto the I picture frame which is divided into n areas, and positioninformation representative of the recording position on the recordingmedium of divided 1 through n areas is recorded; a buffer memory forstoring data in the area which is read; and means for outputting onlydata in the central area which is read.
 4. A digital video signalplayback device according to claim 3 , wherein the data in the centralarea which is read at the time of the special playback is extended toone screen and is outputted for performing the special playback.
 5. Adigital video signal record and playback device for recording andplaying back on a recording medium a digital video signal coded by usinga motion compensation prediction and an orthogonal transform, saiddevice comprising: means for dividing one frame portion of video datainto n areas (n>1) with respect to at least an I picture for anintra-frame coding at the time of recording; means for recording an areawhich comes to the center on the screen in an area unit by giving apriority to the area with respect to the I picture frame which isdivided into n areas while at the same time recording positioninformation representative of the recording position on the recordingmedium of divided 1 through n areas; means for reading at least the Ipicture from the recording medium at the time of the special playback; abuffer memory for storing data of the I picture which is read; andinterpolating means for interpolating an area which cannot be read bythe use of the data of the preceding screen when the whole I picturearea cannot be read.
 6. A digital video signal record and playbackdevice for recording and playing back on a recording medium a digitalvideo signal coded by using a motion compensation prediction and anorthogonal transform, said device comprising: means for dividing oneframe portion of video data into n areas (n>1) with respect to at leastan I picture for an intra-frame coding at the time of recording; meansfor recording an area which comes to the center on the screen in an areaunit by giving a priority to the area with respect to the I pictureframe which is divided into n areas while at the same time recordingposition information representative of the recording position on therecording medium of divided 1 through n areas; means for reading atleast the I picture from the recording medium at the time of the specialplayback; a buffer memory for storing data of the I picture which isread; means for outputting one screen portion of a special playbackpicture in accordance with data for areas 1, 2, - - - , n one by onefrom n consecutive I pictures which are read; and interpolating meansfor interpolating an area which cannot be read by the use of the data ofthe preceding screen when the whole I picture area cannot be read.
 7. Adigital video signal record and playback device for recording andplaying back on a recording medium a digital video signal coded by usinga motion compensation prediction and an orthogonal transform, saiddevice comprising: means for dividing one frame portion of video datainto n areas (n>1) with respect to at least an I picture for anintra-frame coding at the time of recording; means for recording theorder of the area for which recording is started, by scrolling in theunit of GOP of the motion compensation prediction when recording in anarea unit the I picture that is divided into n areas, while at the sametime recording position information representative of the recordingposition on the recording medium of 1 through n areas in the GOP; meansfor reading at least the I picture from the recording medium at the timeof the special playback; a buffer memory for storing data of the Ipicture which is read; means for outputting a special playback picturein accordance with the data of the I picture which is read; andinterpolating means for interpolating an area which cannot be read bythe use of the data of the preceding screen when the whole I picturearea cannot be read.
 8. A digital video signal record and playbackdevice for recording and playing back on a recording medium in the unitof several frames a digital video signal coded in the unit of severalframes in which an I picture for an intra-frame coding, a P picture fora motion compensation prediction in the forward direction, and a Bpicture for the motion compensation prediction by using as referencepictures the I picture and the P picture located before and after intime, said device comprising: means for dividing one frame portion ofvideo data into n areas (n>1) with respect to at least the I picture andthe P picture at the time of recording, and coding the data in the areaunit which is divided into n areas; means for recording an area whichcomes to the center on the screen in an area unit by giving a priorityto the area and giving a priority to the I picture with respect to the Ipicture frame and the P picture frame which are divided into n areaswhile at the same time recording position information representative ofthe recording position on the recording medium of divided 1 through nareas; means for reading at lest the I picture and the P picture fromthe recording medium at the time of the special playback; a buffermemory for storing data of the I picture and the P picture which isread; means for outputting in the unit of frame the data of the Ipicture and the P picture which is read, as a special playback picture;and interpolating means for interpolating an area which cannot be readby the use of the data of the preceding screen when the whole I pictureor the whole P picture area cannot be read.
 9. A digital video signalrecord and playback device for recording and playing back on a recordingmedium in the unit of several frames a digital video signal coded in theunit of several frames in which an I picture for an intra-frame coding,a P picture for a motion compensation prediction in the forwarddirection, and a B picture for the motion compensation prediction byusing as reference pictures the I picture and the P picture locatedbefore and after in time, said device comprising: means for dividing oneframe portion of video data into n areas (n>1) with respect to at leastthe I picture and the P picture at the time of recording, and coding thedata in the area unit which is divided into n areas; means for recordingan area which comes to the center on the screen in an area unit bygiving a priority to the area and giving a priority to the I picturewith respect to the I picture frame and the P picture frame which aredivided into n areas while at the same time recording positioninformation representative of the recording position on the recordingmedium of divided 1 through n areas; means for reading data in the areas1, 2, - - - , n one by one from continuous n I pictures and P pictureswhen decoding one screen portion of the playback picture at the time ofthe special playback; and means for outputting one screen portion of thespecial playback picture in accordance with the data of the I pictureand the P picture which is read; and interpolating means forinterpolating an area which cannot be read by the use of the data of thepreceding screen when the whole I picture or the whole P picture areacannot be read.
 10. A digital video signal record and playback devicefor recording and playing back on a recording medium in the unit ofseveral frames a digital video signal coded in the unit of severalframes in which an I picture for an intra-frame coding, a P picture fora motion compensation prediction in the forward direction, and a Bpicture for the motion compensation prediction by using as referencepictures the I picture and the P picture located before and after intime, said device comprising: means for dividing one frame portion ofvideo data into n areas (n>1) with respect to at least the I picture andthe P picture at the time of recording, and coding the data in the areaunit which is divided into n areas; means for giving a priority to the Ipicture out of the I picture and the P picture which are divided into nareas, and recording the position of the area for record starting, byscrolling in the unit of the I and the P picture frame when recording inan area unit the I picture and the P picture divided into n areas, whileat the same time recording position information representing the recordposition on the recording medium of each area in the GOP; means forreading from the recording medium at least the I picture or the Ppicture at the time of the special playback; a buffer memory for storingdata of the I picture or the P picture which is read; means foroutputting the data of the I picture or the P picture which is read, inthe unit of frame as the special playback picture; and interpolatingmeans for interpolating an area which cannot be read by the use of thedata of the preceding screen when the whole I picture or the whole Ppicture area cannot be read.
 11. A digital video signal playback devicefor reading and playing back data recorded on a recording medium bycoding a digital video signal using a motion compensation prediction andan orthogonal transform, said device comprising: data rearranging meansfor rearranging the data recorded on the recording medium in the orderof data before the division in accordance with header information in apacket and outputting it at the time of the normal playback, the data tobe rearranged being obtained by dividing at least an I picture for anintra-frame coding with a frequency region, a quantization level, or aspace resolution degree to constitute a bitstream of video data in whichdata more important as a picture out of the data divided at least withrespect to the I picture is arranged at the front thereof, and arrangingthe address information of the data which is divided as headerinformation at the front of the bitstream of video data to constitutethe packet; and special playback data output means for performing aspecial playback by decoding data arranged at the front of the recordingmedium to be outputted at the time of the special playback.
 12. Adigital video signal playback method for playing back a digital videosignal coded and recorded by using a motion compensation prediction andan orthogonal transform, said method comprising the steps of:rearranging the data recorded on a recording medium is rearranged in theorder of data before the division in accordance with header informationin a packet and outputting it at the time of the normal playback, thedata to be rearranged being obtained by dividing at least an I picturefor an intra-frame coding with a frequency region, a quantization level,or a space resolution degree to constitute a bitstream of video data inwhich data more important as a picture out of the data divided at leastwith respect to the I picture is arranged at the front thereof, andarranging the address information of the data which is divided as headerinformation at the front of the bitstream of video data to constitutethe packet; and performing a special playback by decoding data arrangedat the front of the recording medium to be outputted at the time of thespecial playback.
 13. A digital video signal record and playback devicefor recording on a recording medium a digital video signal coded byusing a motion compensation prediction and an orthogonal transform andfor reading and playing back the data from the recording medium, saiddevice comprising: means for dividing at least an I picture for anintra-frame coding with a frequency region, a quantization level or aspace resolution; means for constituting a bitstream of video data inwhich data more important as a picture is arranged at the front thereofout of the data divided at least with respect to the I picture; meansfor constituting a packet by arranging address information of thedivided data as header information at the front of the bitstream ofvideo data; means for recording the constituted data on the recordingmedium; data rearranging means for rearranging and outputting data inthe data order before the division in accordance with header informationin the packet at the time of the normal playback; and special playbackdata outputting means for decoding and outputting data arranged at thefront at the time of the special playback for performing the specialplayback.
 14. A digital video signal record and playback method forplaying back a digital signal coded and recorded by using a motioncompensation prediction and an orthogonal transform, said methodcomprising the steps of: dividing at least an I picture for anintra-frame coding with a frequency region, a quantization level or aspace resolution; constituting a bitstream of video data in which datamore important as a picture is arranged at the front thereof out of thedata divided at least with respect to the I picture; recording on therecording medium the data by arranging the address information of thedivided data as header information at the front of the bitstream ofvideo data to constitute a packet; and rearranging and outputting datain the order of data before the division in accordance with headerinformation in the packet at the time of the normal playback, andperforming the special playback by decoding and outputting the dataarranged at the front at the time of the special playback.
 15. A digitalvideo signal record and playback device for recording on a recordingmedium a digital video signal coded by using a motion compensationprediction and an orthogonal transform and playing back the data fromthe recording medium, said device comprising: means for dividing atleast an I picture for an intra-frame coding at the time of recordinginto n areas (n>1) and rearranging the I picture data divided into nareas in the area unit to constitute a bitstream of video data in whichan area which comes to the center on the screen is arranged at the frontthereof; means for recording on the recording medium the data byarranging the address information of the divided area as headerinformation at the front of the bitstream of video data to constitute apacket; data rearranging means for rearranging and outputting the Ipicture data in the area unit in accordance with header informationarranged at the front of the packet at the time of the normal playback;and special playback data output means for performing the specialplayback by outputting only the I picture data which can be read in adefinite time from the front of the packet at the time of the specialplayback.
 16. A digital video signal record and playback method forrecording on a recording medium a digital video signal coded by using amotion compensation prediction and an orthogonal transform and playingback data from the recording medium, said method comprising the stepsof: dividing at least an I picture for an intra-frame coding at the timeof recording into n areas (n>1) and rearranging the I picture datadivided into n areas in the area unit to constitute a bitstream of videodata in which an area which comes to the center on the screen isarranged at the front thereof; recording on the recording medium thedata by arranging the address information of the divided area as headerinformation at the front of the bitstream of video data to constitute apacket; and rearranging and outputting the I picture data in the areaunit in accordance with header information arranged at the front of thepacket at the time of the normal playback, and performing the specialplayback by outputting only the I picture data which can be read in adefinite time from the front of the packet at the time of the specialplayback.
 17. A digital video signal playback device for reading andplaying back data recorded on a recording medium by coding a digitalvideo signal using a motion compensation prediction and an orthogonaltransform, said device comprising: data rearranging means forrearranging and outputting in the unit of area the I picture datarearranged for each area in accordance with the header informationarranged at the front of the packet at the time of the normal playback,with respect to the data recorded on the recording medium, the databeing obtained by dividing at least an I picture for an intra-framecoding into n areas (n>1) and rearranging the I picture data dividedinto n areas in the area unit to constitute a bitstream of video data inwhich an area which comes to the center on the screen is arranged at thefront thereof and by arranging address information of the divided areaas header information at the front of the bitstream of video data toconstitute a packet; and special playback data output means forperforming a special playback by outputting only data which can be readin a definite time from the front of the packet at the time of thespecial playback.
 18. A digital video signal playback method for readingand playing back data recorded on a recording medium by coding a digitalvideo signal by using a motion compensation and an orthogonalconversion, said method comprising the steps of; rearranging andoutputting in the unit of area the I picture data rearranged for eacharea in accordance with the header information arranged at the front ofthe packet at the time of the normal playback, with respect to the datarecorded on the recording medium, the data being obtained by dividing atleast an I picture for an intra-frame coding into n areas (n>1) andrearranging the I picture data divided into n areas in the area unit toconstitute a bitstream of video data in which an area which comes to thecenter on the screen is arranged at the front thereof and by arrangingaddress information of the divided area as header information at thefront of the bitstream of video data to constitute a packet; andperforming a special playback by outputting only data which can be readin a definite time from the front of the packet at the time of thespecial playback.
 19. A digital video signal record and playback devicefor recording on a recording medium a digital video signal coded byusing a motion compensation prediction and an orthogonal transform andplaying back the data from the recording medium, said device comprising:means for dividing at least an I picture for an intra-frame coding atthe time of recording according to a low frequency region and a highfrequency region, a quantization level or a space resolution; means forrearranging the basic data out of at least the divided I picture data ineach area unit on the screen to constitute a bitstream of video data inwhich an area located at the central part of the screen is arranged atthe front; means for arranging the address information of the dividedarea, the data division and picture at the front of the bitstream ofvideo data as header information to constitute a packet therebyrecording the information on the recording medium; data rearrangingmeans for rearranging and outputting data in the unit of area inaccordance with the header information arranged at the front of thepacket at the time of the normal playback; means for rearranging data inthe order before the division; and special playback data output meansfor performing the special playback by outputting only the data whichcan be read within a definite time from the front of the packet at thetime of the special playback.
 20. A digital video signal record andplayback method for recording on a recording medium a digital videosignal coded by using a motion compensation prediction and an orthogonaltransform and playing back the data from the recording medium, saidmethod comprising the steps of: dividing at least an I picture for anintra-frame coding at the time of recording according to a low frequencyregion and a high frequency region, a quantization level or a spaceresolution; rearranging the basic data out of the divided I picture datain each area unit on the screen to constitute a bitstream of video datain which an area located at the central part of the screen is arrangedat the front; arranging the address information of the divided area, thedata division and picture at the front of the bitstream of video data asheader information to constitute a packet thereby recording theinformation on the recording medium; and rearranging and outputting datain the unit of area in accordance with the header information arrangedat the front of the packet at the time of the normal playback, andrearranging the divided data in the original order thereby performingthe special playback by outputting only the data which can be readwithin a definite time from the front of the packet at the time of thespecial playback.
 21. A digital video signal playback device for playingback from a recording medium a digital video signal data coded by usinga motion compensation prediction and an orthogonal transform, saiddevice comprising: data rearranging means for rearranging and outputtingdata recorded on the recording medium in the unit of area in accordancewith the header information arranged at the front of the packet at timeof the normal playback, the data being obtained by dividing at least anI picture for an intra-frame coding at the time of recording accordingto a low frequency region and a high frequency region, a quantizationlevel or a space resolution, and further rearranging the basic data outof at least the divided I picture data in each area unit on the screento constitute a bitstream of video data in which an area located at thecentral part of the screen is arranged at the front, and arranging theaddress information of the divided area, the data division and pictureas header information at the front of the bitstream of video data asheader information to constitute the packet; and means for rearrangingdata in the order before the division; and special playback data outputmeans for performing the special playback by outputting only the datawhich can be read within a definite time from the front of the packet atthe time of the special playback.
 22. A digital video signal playbackmethod for playing back from a recording medium a digital video signaldata coded by using a motion compensation prediction and an orthogonaltransform, said method comprising the steps of: rearranging andoutputting data recorded on the recording medium in the unit of area inaccordance with the header information arranged at the front of thepacket at time of the normal playback the data being obtained bydividing at least an I picture for an intra-frame coding at the time ofrecording according to a low frequency region and a high frequencyregion, a quantization level or a space resolution, and furtherrearranging the basic data out of the divided I picture data in eacharea unit on the screen to constitute a bitstream of video data in whichan area located at the central part of the screen is arranged at thefront, and arranging the address information of the divided area, thedata division and picture as header information at the front of thebitstream of video data to constitute the packet; rearranging thedivided data in the original order; and performing the special playbackby outputting only the data which can be read within a definite timefrom the front of the packet at the time of the special playback.
 23. Adigital video signal record device for recording on a recording medium adigital video signal coded by using a motion compensation prediction andan orthogonal transform, said device comprising: first coding means forcoding under a predetermined condition a video signal comprising a codedpicture including at least a picture subjected to an intra-frame codingout of digital video signals coded by using the motion compensationprediction and the orthogonal transform; second coding means for codinga residual difference component coded by using said first coding meansout of the video signal; and data arranging means for arranging eachoutput data outputted from said first coding means and second codingmeans at a predetermined position in each picture group data for each ofthe picture group data.
 24. A digital video signal record deviceaccording to claim 23 wherein said first coding means codes video datathinned in a predetermined interval with respect to the video signalcomprising the coded picture including at least the picture subjected tothe intra-frame coding.
 25. A digital video signal record deviceaccording to claim 23 , wherein said first coding means codes only alow-frequency region which is subjected to the orthogonal transform. 26.A digital video signal record device according to claim 23 , whereinsaid first coding means roughly quantizes on a quantization level forcoding.
 27. A digital video signal record device for recording on arecording medium a digital video signal coded by using a motioncompensation prediction and an orthogonal transform, said devicecomprising: means for segmenting for each of predetermined bits a videosignal comprising a coded picture including at least a picture subjectedto an intra-frame coding out of digital video signals coded by using themotion compensation prediction and the orthogonal transform; and lowfrequency region extracting means for extracting data of the lowfrequency region from each of the segmented data strings.
 28. A digitalvideo signal playback device for playing back from a recording medium adigital video signal coded by using a motion compensation prediction andan orthogonal transform divided into a low frequency region data and ahigh frequency region data, said device comprising: data rearrangingmeans for rearranging in a predetermined order the low frequency regiondata and the high frequency region data; and mode switching means forselecting either a mode for decoding rearranged data, or a mode forselectively decoding the low frequency region data.
 29. A digital videosignal playback device according to claim 28 , further comprising: dataprocessing means for decoding only data which can be decoded in the casewhere the data is decoded in the mode for decoding only the lowfrequency region data, discarding data which cannot be decoded in thevicinity of the boundary of a predetermined number of bits, andreplacing the obtained high frequency region data with a fixed value forperforming an inverse orthogonal transform.
 30. A digital video signalrecord device for recording on a recording medium a digital video signalcoded by using a motion compensation prediction and an orthogonaltransform, said device comprising: means for adding a block end code toa coded data of each blocks of a video signal comprising a coded pictureincluding at least a picture subjected to an intra-frame coding out ofdigital video signals coded by using the motion compensation predictionand the orthogonal transform when the data reaches a predeterminednumber of bits as low frequency region data; and coding means for codingthe coded data exceeding the predetermined number of bits added with theblock end code as high frequency region data.
 31. A digital video signalplayback device for reading from a recording medium coded data formed bypartitioning with a block end code a low frequency region data and ahigh frequency region data coded based on a motion compensationprediction and an orthogonal transform, said device comprising: datareconstructing means for reconstructing data on the basis of the lowfrequency region data, the high frequency region data and the block endcode; mode switching means for selecting either a mode for decoding thereconstructed data or a mode for selectively decoding only the lowfrequency region data; decoding means for decoding coded datareconstituted on the basis of the output of said mode switching means;and data processing means for replacing the high frequency region datawith a fixed value for an inverse orthogonal transform.
 32. A digitalvideo signal playback device for reading from a recording medium adigital video signal comprising a low resolution component data coded byusing a motion compensation prediction and an orthogonal transform beingthinned in pixel, and a differential component data between the picturebefore thinning in pixel and the picture after thinning in pixel to beinterpolated, said device comprising: means for synthesizing the lowresolution component data and the differential component data; and meansfor decoding the synthesized data.
 33. A digital video signal playbackdevice according to claim 32 , further comprising, mode switching meansfor switching over between a mode for synthesizing and decoding the lowresolution component data and the differential component data and a modefor decoding only the low resolution component data.
 34. A digital videosignal playback device according to claim 32 , further comprising,interpolating means for generating a picture interpolated after decodingat the time of decoding the low resolution picture.
 35. A digital videosignal record device for recording on a recording medium a digital videosignal coded by using a motion compensation prediction and an orthogonaltransform, said device comprising: judging means for judging the degreeof deterioration of a picture when the data is coded and decoded on thebasis of the motion compensation prediction and the orthogonaltransform; adaptive coding means for performing a coding with adaptivelychanging a data rate on the basis of a judgement output from saidjudging means; and information adding means for adding an audio signal,additional information and an error correction code; wherein data rateinformation is multiplexed with the additional information or is writtenin a predetermined region of the recording medium.
 36. A digital videosignal record device for recording on a recording medium a digital videosignal coded by using a motion compensation prediction and an orthogonaltransform, said device comprising: judging means for judging the degreeof deterioration of a picture when the data is coded and decoded on thebasis of the motion compensation prediction and the orthogonaltransform; information adding means for adding an audio signal,additional information and an error correction code; and first codingmeans for coding a video signal thinned at a predetermined interval withrespect to a video signal comprising a coded picture including at leasta picture subjected to an intra-frame coding; and second coding meansfor coding a residual difference component by the coding of the videosignal using said first coding means; wherein the coding is performed insuch a manner that the data rate in either said first coding means orsaid second coding means is adaptively changed on the basis of ajudgement output from said judging means.
 37. A digital video signalrecord device for recording on a recording medium a digital video signalcoded by using a motion compensation prediction and an orthogonaltransform, said device comprising: judging means for judging the degreeof deterioration of a picture when the data is coded and decoded on thebasis of the motion compensation prediction and the orthogonalconversion; information adding means for adding an audio signal,additional information and an error correction code; fist coding meansfor coding only a low frequency region which is subjected to theorthogonal conversion with respect to a video signal comprising a codedpicture including at least a picture subjected to an intra-frame coding;and second coding means for coding a residual difference component bythe coding of the video signal using said first coding means; whereinthe coding is performed in such a manner that the data rate in eithersaid first coding means or said second coding means is adaptivelychanged on the basis of a judgement output from said judging means. 38.A digital video signal record device for recording on a recording mediuma digital video signal coded by using a motion compensation predictionand an orthogonal transform, said device comprising: judging means forjudging the degree of deterioration of a picture when the data is codedand decoded on the basis of the motion compensation prediction and theorthogonal transform; information adding means for adding an audiosignal, additional information and an error correction code; firstcoding means for coding a video signal comprising a coded pictureincluding at least a picture subjected to an intra-frame coding with aquantization at a rough quantization level; and second coding means forcoding a residual difference component by the coding of the video signalusing said first coding means; wherein the coding is performed in such amanner that the data rate in either said first coding means or saidsecond coding means is adaptively changed on the basis of a judgementoutput from said judging means.
 39. A digital video signal playbackdevice for reading data in which a data rate is adaptively variable inaccordance with a picture pattern with respect to the data coded byusing an motion compensation prediction and an orthogonal transform,said device comprising: mode switching means for switching a playbackmode between the normal playback mode and the special playback mode;data rate information extracting means for extracting data rateinformation; and position calculating means for calculating a positionon a recording medium where data for the special playback exists on thebasis of data rate information outputted from said data rate informationextracting means at the time of the special playback mode.
 40. A digitalvideo signal playback device according to claim 39 , further comprising,head position converting means for controlling a head position to aposition on a recording medium in accordance with an output from saidposition calculating means and a special playback speed.
 41. A digitalvideo signal record device for recording on a recording medium a digitalvideo signal coded by using a motion compensation prediction and anorthogonal transform, said device comprising: coding means forperforming a coding with controlling a code amount corresponding to aregion assigned to one picture group formed by a digital video signalcoded on the basis of the motion compensation prediction and theorthogonal transform; code amount comparing means for comparing anoutput from said coding means with a predetermined code amount; and datasupplying means for embedding superfluous data in a space region of apicture group having a space region on the basis of the output from saidcode amount comparing means.
 42. A digital data video signal playbackdevice for reading from a recording medium a digital video signal datacoded by using a motion compensation prediction and an orthogonaltransform to embed data of other picture groups in a space region of apicture group formed on the basis of this coded data, said devicecomprising: data reconstructing means for reconstructing the coded dataof embedded video signal into the original picture group; and datadecoding means for decoding data reconstructed by said datareconstructing means.
 43. A data video signal playback device forgenerating a first and a second decoded data corresponding to a firstand a second coded data in accordance with a predetermined conditionfrom data coded on the basis of a motion compensation prediction and anorthogonal transform and having an arrangement of the first and thesecond coded data at a predetermined position in each picture group,said device comprising: at least one decoding means out of a firstdecoding means for obtaining a playback picture by decoding the firstand the second coded data, a second decoding means for obtaining aplayback picture corresponding to a low frequency region of a picturesubjected to an intra-frame coding, the number of thinned pixels or arough quantization by decoding the first coded data, and a thirddecoding means for obtaining a playback picture corresponding to atleast a picture subjected to the intra-frame coding, a low frequencyregion of a picture subjected to an inter-frame prediction coding, thenumber of thinned pixels or a rough quantization; and mode switchingmeans for switching over among the decoding means as to which of saiddecoding means is used at the time of the special playback, on the basisof the special playback speed.
 44. A digital video signal playbackdevice for playing back from a recording medium a video informationcoded on the basis of a motion compensation prediction and an orthogonaltransform; said device comprising: video data-extracting means forextracting data corresponding to a video signal from a playback code;and video data decode and playback means for decoding and playing backvideo data outputted from said video data extracting means; and modeswitching means for switching over a mode among a normal playback mode,a mode for playing back and displaying either an odd number field or aneven number field, and a mode for playing back and displaying a pictureby reversing an odd number field or an even number field.
 45. A digitalvideo signal playback device for generating a first and a second decodeddata corresponding to a first and a second coded data in accordance witha predetermined condition from data coded on the basis of a motioncompensation prediction and an orthogonal transform, said data having anarrangement of the first and the second coded data at a predeterminedposition in each picture group, said data having a coded data rate beingadaptively variable in accordance with a picture pattern, said devicecomprising: at least one decoding means out of a first decoding meansfor obtaining a playback picture by decoding the first and the secondcoded data, a second decoding means for obtaining a playback picturecorresponding to a low frequency region of a picture subjected to anintra-frame coding, the number of thinned pixels or a rough quantizationby decoding the first coded data, and a third decoding means forobtaining a playback picture corresponding to at least a picturesubjected to the intra-frame coding, a low frequency region of a picturesubjected to an inter-frame prediction coding, the number of thinnedpixels or a rough quantization; and mode switching means for switchingover among the decoding means as to which of said decoding means is usedat the time of the special playback, on the basis of the specialplayback speed.